# Protein Misfolding: Causes, Consequences, and Cellular Defense

Proteins are the workhorses of the cell. They catalyze reactions, transport molecules, provide structural support, and relay signals. But a protein can only perform its job if it folds into the correct three-dimensional shape. When a protein fails to achieve this shape, it is said to be misfolded. Protein misfolding is not a rare curiosity; it is a constant threat that every cell must manage. Understanding why proteins misfold, what happens when they do, and how cells fight back is central to molecular biology and to understanding a large class of human diseases.

## What Is Protein Misfolding?

Protein misfolding is the failure of a polypeptide chain to reach its native, functional three-dimensional structure. Every protein begins as a linear sequence of amino acids linked by peptide bonds. This sequence, dictated by the gene that encodes the protein, contains all the information needed for folding. However, the journey from a floppy chain to a compact, functional structure is fraught with peril. At any point, the chain can become trapped in a non-functional conformation, aggregate with other chains, or be degraded before it ever becomes useful.

### The Importance of Protein Shape

Protein function is inseparable from protein shape. Enzymes have active sites with precise geometries that bind substrates and stabilize transition states. Antibodies have variable regions shaped to recognize specific antigens. Ion channels form pores with exact diameters that allow only certain ions to pass. Even a single amino acid change can alter the shape enough to destroy function. The classic example is sickle cell anemia, where a single glutamic acid-to-valine substitution at position 6 of the β-globin chain causes hemoglobin to polymerize into rigid fibers under low oxygen conditions. The protein is not completely misfolded, but its surface properties are altered enough to drive pathological aggregation.

Shape also determines interactions. A protein that folds correctly exposes specific surfaces for binding partners. A misfolded protein may expose hydrophobic patches that are normally buried in the core. These exposed patches are sticky and drive inappropriate interactions with other proteins, membranes, or nucleic acids.

### How Folding Goes Wrong

Folding goes wrong when the protein fails to navigate its energy landscape to the native state. This can happen for many reasons: a mutation that destabilizes the native state, a cellular stress that denatures partially folded intermediates, or an error in translation that produces a truncated or misincorporated [amino acid sequence](/blog/guides/amino-acid-sequence). The result is a population of molecules that are stuck in non-native conformations. Some of these are simply degraded. Others persist and cause harm.

## The Protein Folding Process

To understand misfolding, you must first understand the normal folding process. Folding begins on the ribosome, even before the polypeptide chain is fully synthesized. The [Ribosome Make Protein](/knowledge/molecular-biology/ribosome-make-protein) machinery itself can influence early folding events, and some domains fold co-translationally as they emerge from the ribosomal exit tunnel.

### The Folding Energy Landscape

The energy landscape theory, first articulated in the 1990s, describes folding as a funnel-shaped landscape. The unfolded state is at the top of the funnel, with high free energy and enormous conformational entropy. The native state is at the bottom, with low free energy and a unique, well-defined structure. The funnel is not smooth; it is rugged, with local minima representing partially folded intermediates and misfolded traps.

For a small protein of about 100 amino acids, the number of possible conformations is astronomically large—roughly 10³⁰ or more. If the protein sampled these randomly, folding would take longer than the age of the universe. Yet most small proteins fold in milliseconds to seconds. The funnel shape solves this problem: the protein does not sample all conformations equally. Instead, it rapidly collapses toward the native state, guided by the burial of hydrophobic residues and the formation of local secondary structure. The ruggedness of the funnel means that some molecules will transiently populate misfolded states, but for most proteins, the native state is sufficiently stable and accessible that folding succeeds.

The free energy difference between the folded and unfolded states is typically only 5–15 kcal/mol for a small protein. This is remarkably small—equivalent to the energy of just a few hydrogen bonds. Consequently, mutations that destabilize the native state by even 2–3 kcal/mol can significantly increase the population of unfolded or misfolded molecules.

### Chaperones and Folding Helpers

In the crowded cellular environment, folding is not left to chance. Molecular chaperones are proteins that assist folding without becoming part of the final structure. The heat shock protein 70 (Hsp70) system is the first line of defense. Hsp70 binds to exposed hydrophobic patches on nascent or partially folded proteins, preventing aggregation. It binds and releases the client protein in cycles driven by ATP hydrolysis. The co-chaperone Hsp40 delivers client proteins to Hsp70 and stimulates its ATPase activity. Nucleotide exchange factors then promote ADP-to-ATP exchange, allowing Hsp70 to release the client.

For larger proteins, the chaperonin systems provide an isolated folding chamber. In bacteria, the GroEL/GroES system forms a barrel-shaped complex. GroEL is a heptameric ring that binds unfolded proteins in its central cavity. GroES caps the chamber, and ATP hydrolysis drives a conformational change that encapsulates the client in a hydrophilic environment, allowing it to fold without interference from other cellular components. The eukaryotic equivalent is the TRiC/CCT complex, which is required for the folding of actin and tubulin.

For a deeper look at how chaperones function, see the article on [Chaperone Protein](/knowledge/molecular-biology/chaperone-protein). Chaperones do not dictate the final structure; they only increase the efficiency of folding by reducing aggregation and unfolding misfolded states.

## Types of Protein Misfolding

Misfolding is not a single phenomenon. It manifests in several distinct forms, each with different biophysical properties and biological consequences.

### Amyloid Fibrils

Amyloid fibrils are highly ordered, insoluble protein aggregates with a characteristic cross-β structure. In this structure, β-strands run perpendicular to the fibril axis, forming continuous β-sheets that extend along the length of the fibril. Amyloid fibrils are typically 7–13 nm in diameter and can be microns long. They bind the dye Congo red, producing apple-green birefringence under polarized light, and thioflavin T, which fluoresces upon binding.

Amyloid formation is a nucleation-dependent process. It begins with a slow lag phase during which oligomeric nuclei form. Once a nucleus is formed, fibril elongation proceeds rapidly. The lag phase can be shortened by seeding—adding pre-formed fibrils to a solution of monomeric protein. This phenomenon is relevant to disease, as it may explain the spread of pathology between cells and tissues.

Remarkably, amyloid formation is not limited to disease-associated proteins. Many proteins that are perfectly functional in their native state can be induced to form amyloid under destabilizing conditions. This suggests that amyloid formation is a generic property of polypeptide chains, not a special feature of a few "bad" proteins.

### Amorphous Aggregates

Amorphous aggregates are disorganized clumps of misfolded protein. Unlike amyloid fibrils, they lack regular structure. They form when partially folded intermediates expose hydrophobic surfaces that associate non-specifically. Amorphous aggregates are often the result of severe stress, such as heat shock or oxidative damage, that causes widespread [protein denaturation](/knowledge/molecular-biology/protein-denaturation). They are generally less toxic than amyloid oligomers but can still sequester essential proteins and disrupt cellular function.

### Misfolded but Soluble

Some misfolded proteins remain soluble but are functionally inactive. These are trapped in a non-native conformation that is stable enough to persist. They may be recognized by chaperones and refolded, or they may be targeted for degradation. Soluble misfolded states are often the substrates for the unfolded protein response and the ubiquitin-proteasome system.

## Mechanisms of Misfolding

Misfolding arises from a combination of intrinsic protein properties and extrinsic cellular conditions. Understanding these mechanisms is essential for designing therapeutic interventions.

### Genetic Mutations

Mutations are the most direct cause of misfolding. A single nucleotide change can alter the [amino acid sequence](/blog/guides/amino-acid-sequence), affecting the stability of the native state, the kinetics of folding, or the propensity to aggregate. For example, in cystic fibrosis, the most common mutation is a deletion of phenylalanine at position 508 (ΔF508) in the cystic fibrosis transmembrane conductance regulator (CFTR). This mutation causes the protein to misfold in the endoplasmic reticulum, where it is recognized and degraded before it can reach the plasma membrane. The result is loss of chloride channel function.

Mutations can also increase aggregation propensity. In Huntington's disease, an expansion of a CAG trinucleotide repeat in the huntingtin gene produces a protein with an abnormally long polyglutamine tract. The expanded polyglutamine tract is intrinsically aggregation-prone, and the protein forms amyloid-like inclusions in neurons. The age of onset correlates inversely with the length of the repeat: longer repeats cause earlier disease.

### Cellular Stress and pH

Environmental conditions profoundly affect protein folding. Heat stress increases the kinetic energy of molecules, destabilizing the native state and populating partially folded intermediates. Oxidative stress can modify amino acid side chains, particularly cysteine residues, forming disulfide bonds that lock proteins in non-native conformations. Changes in pH alter the protonation state of amino acid side chains, affecting electrostatic interactions that stabilize the native structure.

The endoplasmic reticulum (ER) is particularly sensitive to these stresses. The ER is the site of folding for secretory and membrane proteins, and it maintains an oxidizing environment that promotes disulfide bond formation. When the load of unfolded proteins exceeds the folding capacity of the ER, a condition called ER stress ensues. This triggers the unfolded protein response (UPR), which we will discuss later.

### Post-Translational Modifications

Post-translational modifications can either promote or prevent misfolding. Glycosylation, the addition of sugar moieties to asparagine residues, is a common modification in the ER. N-linked glycans serve as quality control tags: they are recognized by lectin chaperones such as calnexin and calreticulin, which retain the protein in the ER until folding is complete. Improper glycosylation can lead to misfolding and degradation.

Phosphorylation, acetylation, and other modifications can also affect folding by altering the charge and hydrophobicity of specific regions. For a comprehensive overview of how modifications influence protein fate, see [Post Translational Protein Modification](/knowledge/molecular-biology/post-translational-protein-modification).

## Consequences of Protein Misfolding

The consequences of misfolding are twofold: loss of the protein's normal function and gain of a toxic function.

### Loss of Function

When a protein misfolds, it cannot perform its biological role. If the protein is an enzyme, its catalytic activity is lost. If it is a structural protein, the cell's architecture is compromised. Loss of function is the primary consequence in many genetic diseases. In cystic fibrosis, the misfolded CFTR channel never reaches the membrane, so chloride transport is abolished. In α1-antitrypsin deficiency, a misfolded variant of the protease inhibitor accumulates in the liver, while the lungs are left unprotected from neutrophil elastase, leading to emphysema.

Loss of function can also result from sequestration. Misfolded proteins may aggregate and trap other proteins, including those that are perfectly folded. This is particularly damaging when the sequestered proteins are essential for cell survival.

### Gain of Toxic Function

In many neurodegenerative diseases, misfolded proteins acquire a toxic gain of function. The toxic species are not necessarily the large amyloid fibrils that are visible under the microscope. Increasing evidence points to soluble oligomers as the primary toxic entities. These oligomers can disrupt membrane integrity, forming pores that allow uncontrolled ion flux. They can also bind to and sequester other proteins, interfering with their function.

The toxicity of misfolded proteins is also linked to the cellular stress response. When misfolded proteins accumulate, they overwhelm the proteostasis network, leading to ER stress, mitochondrial dysfunction, and oxidative damage. The cell may ultimately undergo apoptosis, contributing to tissue degeneration.

## Protein Misfolding in Disease

Protein misfolding is implicated in over 50 human diseases, collectively called protein misfolding disorders or proteopathies. These are broadly divided into neurodegenerative diseases and systemic amyloidoses.

### Neurodegenerative Diseases

Alzheimer's disease is the most common neurodegenerative disorder. It is characterized by two types of aggregates: extracellular amyloid plaques composed of amyloid-β (Aβ) peptide, and intracellular neurofibrillary tangles composed of hyperphosphorylated tau protein. Aβ is generated by proteolytic cleavage of the amyloid precursor protein (APP) by β-secretase (BACE1) and γ-secretase. The predominant forms are Aβ40 and Aβ42, with Aβ42 being more aggregation-prone. The "amyloid cascade hypothesis" posits that Aβ aggregation is the initiating event, leading to tau pathology, synaptic dysfunction, and neuronal death.

Parkinson's disease is characterized by the loss of dopaminergic neurons in the substantia nigra and the presence of Lewy bodies, which are intracellular inclusions rich in α-synuclein. α-Synuclein is a small, intrinsically disordered protein that can adopt α-helical structure upon binding to membranes. Under pathological conditions, it misfolds into β-sheet-rich oligomers and fibrils. Mutations in the SNCA gene encoding α-synuclein, as well as duplication or triplication of the gene, cause familial forms of Parkinson's disease.

Huntington's disease is caused by a CAG repeat expansion in the huntingtin gene. The mutant protein forms nuclear and cytoplasmic inclusions. Unlike Alzheimer's and Parkinson's, Huntington's is a monogenic disease with complete penetrance, making it a valuable model for studying the mechanisms of polyglutamine toxicity.

Prion diseases, including Creutzfeldt-Jakob disease in humans and bovine spongiform encephalopathy in cattle, are caused by the misfolding of the prion protein (PrP). The misfolded form, PrPSc, is infectious: it can convert the normal cellular prion protein (PrPC) into the misfolded conformation. This is the only known disease mechanism where a protein itself is the infectious agent.

### Systemic Amyloidoses

Systemic amyloidoses involve the deposition of amyloid fibrils in multiple organs. In AL amyloidosis, the fibrils are composed of immunoglobulin light chains produced by a clonal population of plasma cells. In AA amyloidosis, the fibrils are composed of serum amyloid A protein, an acute-phase reactant that is elevated during [chronic inflammation](/knowledge/veterinary-medicine/veterinary-pathology-microbiology/chronic-inflammation-causes-and-morphologic-features). In transthyretin (TTR) amyloidosis, the fibrils are composed of TTR, a transport protein for thyroxine and retinol-binding protein. TTR is a tetramer, and its dissociation into monomers is the rate-limiting step for amyloid formation. The V30M mutation in TTR is the most common cause of familial amyloid polyneuropathy.

## How Cells Prevent and Respond to Misfolding

Cells have evolved a sophisticated quality control network to prevent misfolding and to deal with misfolded proteins when they arise. This network is collectively called the proteostasis network.

### The Unfolded Protein Response (UPR)

The UPR is a signaling pathway activated by ER stress. It is mediated by three ER-resident sensors: IRE1, PERK, and ATF6. Under normal conditions, these sensors are kept inactive by binding to the chaperone BiP (GRP78). When misfolded proteins accumulate, BiP is titrated away, releasing the sensors and activating their signaling cascades.

IRE1 has both kinase and endoribonuclease activity. Upon activation, it splices the mRNA for XBP1, producing a potent [transcription factor](/knowledge/molecular-biology/transcription-factor) that upregulates genes involved in ER folding, ER-associated degradation (ERAD), and lipid synthesis. PERK phosphorylates the translation initiation factor eIF2α, globally reducing protein synthesis to decrease the load on the ER. ATF6 is transported to the Golgi, where it is cleaved by site-1 and site-2 proteases, releasing a cytosolic fragment that translocates to the nucleus and activates transcription of chaperone genes.

If ER stress is prolonged and the UPR cannot restore homeostasis, the pathway switches from pro-survival to pro-apoptotic. This is mediated by the transcription factor CHOP, which downregulates the anti-apoptotic protein Bcl-2 and upregulates pro-apoptotic factors.

### Proteasomal Degradation

The ubiquitin-proteasome system is the primary pathway for degrading misfolded proteins in the cytosol and nucleus. The process involves two steps: ubiquitination and proteasomal degradation. Ubiquitin is a 76-amino-acid protein that is covalently attached to lysine residues on target proteins through a cascade of enzymes: E1 (ubiquitin-activating), E2 (ubiquitin-conjugating), and E3 (ubiquitin-ligating). Polyubiquitin chains linked through lysine 48 of ubiquitin are the canonical signal for proteasomal degradation.

The 26S proteasome is a large complex composed of a 20S core particle and two 19S regulatory particles. The 20S core is a barrel-shaped structure with proteolytic active sites facing the interior. The 19S regulatory particles recognize ubiquitinated substrates, deubiquitinate them, unfold them, and translocate them into the core for degradation. The proteasome degrades proteins into peptides of 3–22 amino acids, which can be further processed for antigen presentation.

Misfolded proteins in the ER are degraded by ERAD. They are retrotranslocated to the cytosol through the Sec61 translocon or the Derlin-1 channel, ubiquitinated by ER-resident E3 ligases such as HRD1, and degraded by the proteasome. For more details on this pathway, see [Targeted Protein Degradation](/knowledge/molecular-biology/targeted-protein-degradation) and [Proteasome Protein Degradation](/knowledge/molecular-biology/proteasome-protein-degradation).

### Autophagy

Autophagy is a catabolic process that delivers cytoplasmic material to lysosomes for degradation. There are three forms: macroautophagy, microautophagy, and chaperone-mediated autophagy. Macroautophagy involves the formation of double-membrane vesicles called autophagosomes that engulf cytoplasmic cargo and fuse with lysosomes. This pathway is particularly important for degrading protein aggregates that are too large for the proteasome.

Chaperone-mediated autophagy is selective: proteins containing a KFERQ-like motif are recognized by Hsp70, translocated across the lysosomal membrane via LAMP-2A, and degraded. This pathway is important for the clearance of specific misfolded proteins and is impaired in aging.

The interplay between the proteasome and autophagy is complex. When the proteasome is overwhelmed, autophagy is upregulated. Conversely, inhibition of autophagy leads to accumulation of ubiquitinated proteins. The two systems are coordinated by [transcription factors](/knowledge/molecular-biology/transcription-factor) such as TFEB, which regulates lysosomal biogenesis and autophagy genes. For a broader view of degradation pathways, see [Forms of Protein Degradation](/knowledge/molecular-biology/forms-of-protein-degradation) and [Two Phases of Protein Degradation](/knowledge/molecular-biology/two-phases-of-protein-degradation).

## Methods to Study Protein Misfolding

Studying protein misfolding requires a combination of biophysical, biochemical, and cell-based approaches. Each method provides a different piece of the puzzle.

### Biophysical Techniques

Circular dichroism (CD) spectroscopy measures the difference in absorption of left- and right-circularly polarized light. Far-UV CD (190–250 nm) reports on secondary structure: α-helices have characteristic minima at 208 and 222 nm, while β-sheets have a minimum at 218 nm. Near-UV CD (250–350 nm) reports on tertiary structure by monitoring the environment of aromatic residues. CD is useful for following unfolding transitions as a function of temperature, denaturant concentration, or pH.

Fluorescence spectroscopy is used to monitor folding and aggregation. Intrinsic tryptophan fluorescence is sensitive to the local environment: a buried tryptophan has a blue-shifted emission maximum compared to an exposed one. Extrinsic dyes such as thioflavin T and 1-anilinonaphthalene-8-sulfonate (ANS) bind to amyloid fibrils and exposed hydrophobic surfaces, respectively, providing a readout of aggregation.

Cryo-electron microscopy (cryo-EM) has revolutionized the study of amyloid fibrils. With the advent of direct electron detectors and improved image processing algorithms, cryo-EM can now determine the atomic structures of amyloid fibrils. These structures reveal the precise arrangement of β-strands and the interactions that stabilize the fibril. For example, cryo-EM structures of α-synuclein fibrils from patients with multiple system atrophy differ from those of fibrils from patients with Parkinson's disease, suggesting that different fibril conformations, or "strains," may underlie different disease phenotypes.

### Cell-Based Assays

Cell-based assays are essential for studying misfolding in a physiological context. The most common approach is to express a misfolding-prone protein fused to a fluorescent reporter and monitor its localization, aggregation, and degradation by [fluorescence microscopy](/knowledge/diagnostics/imaging/fluorescence-microscopy-principles-applications-and-image-acquisition). The green fluorescent protein (GFP) can be fused to a protein of interest; if the protein misfolds and aggregates, the GFP will form puncta that are visible as bright spots.

The split-GFP assay is a clever variant. GFP is split into two fragments: one is fused to the protein of interest, and the other is expressed separately. If the protein of interest folds correctly, the two fragments come into proximity and reconstitute a functional fluorophore. If the protein misfolds, no fluorescence is observed. This assay can be used to screen for drugs that promote correct folding.

The unfolded protein response can be monitored using reporter genes under the control of UPR-responsive promoters. For example, a luciferase gene driven by the XBP1 promoter will produce luminescence when the UPR is activated. This provides a quantitative readout of ER stress.

## Common Misconceptions and Pitfalls

Several misconceptions about protein misfolding are widespread, even among students of biology. Clarifying these is essential for a correct understanding.

### Misfolding Is Not Always Harmful

Not all misfolding leads to disease. Many misfolded proteins are simply degraded and recycled. The cell's quality control systems are remarkably efficient, and the vast majority of misfolded proteins never accumulate to toxic levels. Moreover, some proteins are intrinsically disordered—they do not have a single stable structure—yet they are perfectly functional. [Intrinsically disordered proteins](/knowledge/bioinformatics/intrinsically-disordered-proteins-and-computational-structural-classification) are involved in signaling, transcription, and cell cycle regulation. Their lack of structure is a feature, not a bug.

### Chaperones Do More Than Fold

Chaperones are often described as "folding helpers," but their functions are more diverse. They also disaggregate existing aggregates, target misfolded proteins for degradation, and regulate the activity of native proteins. Hsp70, for example, is involved in protein translocation across membranes, clathrin uncoating, and the regulation of steroid hormone receptor activity. The [Chaperone Protein](/knowledge/molecular-biology/chaperone-protein) article provides a more detailed account.

### Folding Is Not a One-Way Street

Proteins are not static structures. They are in dynamic equilibrium with partially unfolded states. Many proteins undergo conformational changes as part of their function—enzymes cycle through open and closed states, ion channels open and close, and motor proteins move along cytoskeletal tracks. The native state is not a single structure but an ensemble of closely related conformations. This dynamic nature means that folding and unfolding are continuous processes, and the line between "folded" and "misfolded" is not always sharp.

## Frequently Asked Questions

### What is protein misfolding?

Protein misfolding is the failure of a polypeptide chain to achieve its correct, functional three-dimensional structure. It can result in loss of function, aggregation, or toxicity.

### What are some examples of protein misfolding diseases?

Alzheimer's disease (amyloid-β and tau), Parkinson's disease (α-synuclein), Huntington's disease (huntingtin with expanded polyglutamine), cystic fibrosis (ΔF508 CFTR), and prion diseases (PrPSc) are prominent examples.

### What are the types of protein misfolding?

Misfolding can produce amyloid fibrils (ordered, β-sheet-rich aggregates), amorphous aggregates (disorganized clumps), or soluble but non-functional conformations.

### What is the mechanism of protein misfolding?

Misfolding is caused by mutations, cellular stress (heat, oxidative stress, pH changes), errors in translation, and defective post-translational modifications. These factors destabilize the native state or promote non-native interactions.

### How do cells prevent protein misfolding?

Cells use molecular chaperones to assist folding, the unfolded protein response to reduce ER stress, the ubiquitin-proteasome system to degrade misfolded proteins, and autophagy to clear aggregates.

### Can protein misfolding be reversed?

Yes, in some cases. Chaperones such as Hsp70 can bind to misfolded proteins and, using ATP hydrolysis, unfold them and allow them to refold. Small molecules called pharmacological chaperones can stabilize the native state and are being developed as therapeutics.

### Why is protein misfolding important?

Protein misfolding is important because it underlies a large class of diseases and because it represents a fundamental challenge in cell biology. Understanding misfolding helps us understand how cells maintain protein homeostasis and provides targets for therapeutic intervention.

## Key Takeaways

- Protein misfolding is the failure to achieve the native three-dimensional structure, leading to loss of function or toxic gain of function.
- Folding is guided by the energy landscape, with chaperones assisting the process and preventing aggregation.
- Misfolding can produce amyloid fibrils, amorphous aggregates, or soluble non-functional states.
- Causes include genetic mutations, cellular stress, and errors in translation or post-translational modification.
- Cells defend against misfolding through chaperones, the unfolded protein response, the ubiquitin-proteasome system, and autophagy.
- Protein misfolding is central to many neurodegenerative and systemic diseases, including Alzheimer's, Parkinson's, and Huntington's diseases.
- Studying misfolding requires a combination of biophysical techniques (CD, fluorescence, cryo-EM) and cell-based assays.

## Further Reading

- Chaudhuri TK, Paul S. *Protein-misfolding diseases and chaperone-based therapeutic approaches*. The FEBS journal. 2006. [PubMed 16689923](https://doi.org/10.1111/j.1742-4658.2006.05181.x)
- Soto C, Pritzkow S. *Protein misfolding, aggregation, and conformational strains in neurodegenerative diseases*. Nature neuroscience. 2018. [PubMed 30250260](https://doi.org/10.1038/s41593-018-0235-9)
- Wang M, Kaufman RJ. *Protein misfolding in the endoplasmic reticulum as a conduit to human disease*. Nature. 2016. [PubMed 26791723](https://doi.org/10.1038/nature17041)
- Hartl FU. *Protein Misfolding Diseases*. Annual review of biochemistry. 2017. [PubMed 28441058](https://doi.org/10.1146/annurev-biochem-061516-044518)
- Haque MM, Bayford R. *Protein Misfolding Thermodynamics*. The journal of physical chemistry letters. 2019. [PubMed 31091883](https://doi.org/10.1021/acs.jpclett.9b00852)
- Hofmann C, Katus HA, Doroudgar S. *Protein Misfolding in Cardiac Disease*. Circulation. 2019. [PubMed 31034286](https://doi.org/10.1161/CIRCULATIONAHA.118.037417)

## Related Clinical & Scientific Guides

* [MAPK Pathway: Mechanism, Function, and Clinical Relevance](/knowledge/molecular-biology/mapk-pathway)
* [Mammalian Cell Culture Bioreactors: A Practical Guide](/knowledge/molecular-biology/mammalian-cell-culture-bioreactor)
* [Nucleotide Formation: Biosynthesis and Assembly of DNA/RNA Building Blocks](/knowledge/molecular-biology/nucleotide-formation)