# RNA Location: Types, Functions, and Cellular Distribution

## Introduction to RNA Location

RNA location refers to the precise subcellular distribution of RNA molecules—where specific transcripts reside within a cell at any given time. This is not a passive consequence of diffusion; rather, it is an actively regulated process that determines when and where proteins are synthesized. The spatial organization of RNA is fundamental to gene expression because translation can occur locally, allowing cells to produce proteins precisely where they are needed, respond rapidly to local stimuli, and establish asymmetric protein distributions that underpin cell polarity and development.

The eukaryotic cell is compartmentalized, and each compartment imposes distinct constraints on RNA metabolism. [Transcription occurs in the nucleus](/knowledge/molecular-biology/transcription-occur-in-the-nucleus), but translation occurs predominantly in the cytoplasm. Between these two events, RNA must be processed, exported, transported, and localized. Failure to properly localize RNA leads to developmental defects, neurological disorders, and cellular dysfunction. Understanding RNA location therefore requires knowledge of the RNA types involved, the nuclear and cytoplasmic machinery that directs their movement, and the methods used to visualize and quantify their positions.

## The Major Types of RNA and Their Locations

RNA molecules are classified by their function and, consequently, by their typical cellular locations. The table below summarizes the major RNA classes and their primary subcellular distributions.

| RNA Type | Primary Location | Function |
|----------|------------------|----------|
| Messenger RNA (mRNA) | Cytoplasm (after nuclear export); some retained in nucleus | Template for protein synthesis |
| Transfer RNA (tRNA) | Cytoplasm; imported into mitochondria in some organisms | Delivers amino acids to ribosomes |
| Ribosomal RNA (rRNA) | Nucleolus (synthesis); cytoplasm (as ribosome components) | Catalytic and structural core of ribosomes |
| Small Nuclear RNA (snRNA) | Nucleus (splicing speckles, Cajal bodies) | Splicing and other RNA processing |
| Small Nucleolar RNA (snoRNA) | Nucleolus | rRNA modification and processing |
| MicroRNA (miRNA) | Cytoplasm (RISC complexes); nucleus (some) | Post-transcriptional gene silencing |
| Long Non-Coding RNA (lncRNA) | Nucleus or cytoplasm depending on transcript | Diverse regulatory roles |
| Piwi RNA (piRNA) | Nucleus and cytoplasm (germ cells) | Transposon silencing |

### Messenger RNA (mRNA) Location

Messenger RNA is synthesized in the nucleus by RNA polymerase II as a precursor (pre-mRNA). During transcription, the pre-mRNA undergoes capping at the 5′ end, splicing to remove introns, and cleavage and polyadenylation at the 3′ end. Only after these processing events are complete is the mature mRNA exported through the nuclear pore complex to the cytoplasm. In the cytoplasm, mRNA can exist in two states: free in the cytosol or associated with ribosomes for translation. A significant fraction of mRNA is also localized to specific cytoplasmic regions, such as the leading edge of migrating cells, the dendrites of neurons, or the posterior pole of developing embryos.

Not all mRNA is exported immediately. Some transcripts are retained in the nucleus, either transiently for quality control or stably as part of regulatory mechanisms. For example, certain mRNAs containing premature stop codons are detected by the nonsense-mediated decay pathway and degraded in the nucleus before export. Additionally, some lncRNAs and certain mRNAs are retained at their transcription sites to modulate chromatin structure or sequester [RNA-binding proteins](/knowledge/molecular-biology/rna-binding-protein).

### Transfer RNA (tRNA) and Ribosomal RNA (rRNA) Location

Transfer RNA is transcribed in the nucleus by RNA polymerase III, then processed and modified before export to the cytoplasm. In the cytoplasm, tRNA shuttles between the aminoacyl-tRNA synthetases (which charge it with its cognate amino acid) and the ribosome, where it decodes the mRNA codon. A subset of tRNAs is imported into mitochondria in many organisms, including yeast and plants, to support mitochondrial translation. This import requires specific protein machinery and is discussed further in the organelle section.

Ribosomal RNA is synthesized in the nucleolus, a specialized nuclear body. The 45S pre-rRNA transcript is processed into the 18S, 5.8S, and 28S rRNAs (in humans), which are then assembled with ribosomal proteins into the small and large ribosomal subunits. These subunits are exported to the cytoplasm, where they associate with mRNA to form functional ribosomes. The 5S rRNA is transcribed outside the nucleolus and imported into it for assembly. Thus, rRNA location is dynamic: nucleolar during synthesis, nuclear during assembly, and cytoplasmic once assembled into ribosomes.

### Non-coding RNAs and Their Locations

Non-coding RNAs (ncRNAs) are a diverse group of transcripts that do not encode proteins. Their locations are as varied as their functions. [Small Nuclear RNA](/knowledge/molecular-biology/small-nuclear-rna) (snRNA) is predominantly nuclear, where it forms the core of the spliceosome. U1, U2, U4, U5, and U6 snRNAs are enriched in nuclear speckles—interchromatin granules that serve as storage and assembly sites for splicing factors. During active splicing, snRNAs are recruited to transcription sites.

Small nucleolar RNAs (snoRNAs) localize to the nucleolus, where they guide the 2′-O-methylation and pseudouridylation of rRNA. MicroRNAs (miRNAs) are processed in the nucleus from primary transcripts, exported as precursor hairpins, and then loaded into the RNA-induced silencing complex (RISC) in the cytoplasm. Some miRNAs are also found in the nucleus, where they can regulate gene expression at the transcriptional level. Long non-coding RNAs (lncRNAs) show the most variable localization: some, like XIST, remain in the nucleus to coat the inactive X chromosome, while others, such as certain cytoplasmic lncRNAs, regulate mRNA stability or translation. [Piwi RNA](/knowledge/molecular-biology/piwi-rna) (piRNA) is found in both the nucleus and cytoplasm of germ cells, where it silences [transposable elements](/knowledge/molecular-biology/transposable-element).

## Nuclear RNA Localization

The nucleus is not a homogeneous compartment; it contains distinct subdomains where RNA synthesis, processing, and retention occur. RNA localization within the nucleus is tightly coupled to transcription and processing.

### Transcription and Processing in the Nucleus

Transcription by RNA polymerase II occurs at discrete sites called transcription factories, which are clusters of active genes and their associated polymerases. As the pre-mRNA is synthesized, it is co-transcriptionally processed: the 5′ cap is added when the transcript is only ~20–30 nucleotides long, and splicing factors associate with the nascent RNA as introns are recognized. This coupling ensures that processing is efficient and that only properly processed mRNAs are exported.

Splicing itself occurs largely co-transcriptionally. The spliceosome, composed of snRNPs (small nuclear ribonucleoproteins) and numerous accessory factors, assembles on the pre-mRNA while it is still tethered to the DNA template. After splicing, the exon junction complex (EJC) is deposited upstream of each exon-exon junction. The EJC marks the mRNA as properly spliced and influences downstream events, including export, localization, and translation. mRNAs that fail to splice correctly are retained in the nucleus and targeted for [RNA Degradation](/knowledge/molecular-biology/rna-degradation).

### Nuclear Bodies and RNA Retention

Nuclear speckles are dynamic structures enriched in splicing factors, including snRNPs and SR proteins. They are not sites of active splicing but rather storage and recycling centers. When transcription is upregulated, splicing factors are recruited from speckles to transcription sites. Speckles therefore represent a reservoir of RNA processing machinery whose distribution changes with transcriptional activity.

The nucleolus is the site of rRNA synthesis and ribosome assembly. It is organized into three subcompartments: the fibrillar center (FC), the dense fibrillar component (DFC), and the granular component (GC). Transcription of rRNA occurs at the boundary of the FC and DFC, processing in the DFC, and subunit assembly in the GC. The nucleolus also sequesters certain mRNAs and proteins, acting as a stress-responsive storage site. For example, under stress conditions, specific mRNAs are retained in the nucleolus to prevent their translation.

RNA retention in the nucleus is an active process. Some lncRNAs, such as XIST, are retained at their transcription site by tethering to the nuclear matrix or to chromatin. This retention is mediated by specific RNA-binding proteins and by the RNA itself through repetitive elements that recruit silencing factors. Nuclear retention can also serve as a regulatory mechanism: certain mRNAs are held in the nucleus until a signal triggers their release and export.

## Cytoplasmic RNA Localization

Once mRNA reaches the cytoplasm, it is not uniformly distributed. Many transcripts are actively transported to specific subcellular regions, where their translation produces proteins at the correct location. This process is particularly important in large or polarized cells, where diffusion alone would be too slow or imprecise.

### Mechanisms of mRNA Localization

Three primary mechanisms direct mRNA to specific cytoplasmic locations: active transport along the cytoskeleton, local entrapment, and protection from degradation in specific regions.

Active transport is the best-characterized mechanism. In this process, an mRNA is recognized by [RNA Binding Protein](/knowledge/molecular-biology/rna-binding-protein) (RBPs) that link the transcript to motor proteins. In Drosophila embryos, for example, the mRNA encoding the anterior determinant Bicoid is transported along microtubules by the motor protein dynein. The 3′ untranslated region (UTR) of bicoid mRNA contains localization elements that are bound by the RBP Egalitarian and the dynein cofactor Bicaudal-D. Similarly, the posterior determinant Oskar mRNA is transported by kinesin, a plus-end-directed motor. In neurons, mRNAs such as β-actin are transported into dendrites and axons along microtubules, where they are translated in response to synaptic activity.

Local entrapment involves the anchoring of mRNA at a specific site once it arrives. This is often mediated by the actin cytoskeleton. In budding yeast, the mRNA encoding the [transcription factor](/knowledge/molecular-biology/transcription-factor) Ash1 is transported to the bud tip by the type V myosin motor Myo4, and then anchored there by the RBP She3 and cortical actin. This localizes Ash1 protein to the daughter cell, ensuring that the mother cell and daughter cell have different mating types.

Protection from degradation is a less direct mechanism. In some cases, mRNA is degraded throughout the cytoplasm except in a specific region where protective factors stabilize it. This mechanism is used in Xenopus oocytes, where Vg1 mRNA is degraded everywhere except the vegetal pole, where it is protected by RBPs.

### Localized Translation and Cell Polarity

The functional consequence of mRNA localization is localized translation. By concentrating mRNA at a specific site, the cell ensures that the encoded protein is synthesized where it is needed, without requiring protein diffusion. This is critical for establishing and maintaining cell polarity.

In migrating fibroblasts, β-actin mRNA is localized to the leading edge, where actin polymerization drives membrane protrusion. The localization is mediated by the RBP ZBP1 (zipcode-binding protein 1), which binds to a zipcode element in the 3′ UTR of β-actin mRNA. Phosphorylation of ZBP1 by Src kinase releases the mRNA, allowing translation. This spatial control ensures that new actin monomers are added at the leading edge, not throughout the cell.

In neurons, mRNA localization underlies synaptic plasticity. Dendritic mRNAs, such as those encoding CaMKIIα and Arc, are transported to dendrites in RNA granules—large ribonucleoprotein complexes that contain multiple mRNAs and RBPs. Upon synaptic stimulation, these mRNAs are locally translated, providing new protein for synaptic strengthening. This local translation is essential for long-term potentiation, a cellular correlate of memory.

## RNA Localization in Organelles

RNA is not confined to the nucleus and cytoplasm; specific RNAs are also targeted to membrane-bound organelles. This targeting requires dedicated import machinery and often involves signal sequences within the RNA itself.

### Mitochondrial RNA Import

Mitochondria contain their own genome and translation system, but they import most of their proteins from the cytoplasm. In addition, many organisms import nuclear-encoded tRNAs and, in some cases, mRNAs into mitochondria. This import is best characterized in yeast and plants.

In yeast, tRNA import into mitochondria requires the mitochondrial outer membrane protein Tom20 and the inner membrane protein Tim44, which are part of the general protein import machinery. The tRNA is recognized by its D-loop and T-loop structures, and import is ATP-dependent. In plants, a larger set of tRNAs is imported, and the process involves additional factors, including the voltage-dependent anion channel (VDAC) in the outer membrane.

The function of mitochondrial tRNA import is to supplement the limited set of tRNAs encoded by the [mitochondrial genome](/blog/guides/mitochondrial-genome). In humans, all 22 tRNAs required for mitochondrial translation are encoded by mitochondrial DNA, so no import is needed. However, in organisms with reduced mitochondrial genomes, tRNA import is essential. Some mRNAs are also imported into mitochondria, particularly in plants and protozoa, where they are translated on mitochondrial ribosomes.

### Endoplasmic Reticulum and Membrane-Bound Ribosomes

The endoplasmic reticulum (ER) is the site of synthesis for secretory and membrane proteins. mRNA encoding these proteins is targeted to the ER co-translationally. The mechanism begins with the signal peptide, a hydrophobic sequence at the N-terminus of the nascent protein. As the ribosome translates the mRNA, the signal peptide emerges and is recognized by the signal recognition particle (SRP). SRP binds to the ribosome-nascent chain complex and pauses translation. The SRP-ribosome complex then docks at the ER membrane via the SRP receptor, and the nascent chain is threaded through the Sec61 translocon. Translation resumes, and the protein is translocated into the ER lumen or inserted into the membrane.

This process means that mRNA encoding secretory proteins is localized to the ER membrane, not free in the cytosol. The mRNA itself is not actively transported; rather, the ribosome-nascent chain complex is targeted, and the mRNA remains associated with the ER-bound ribosome. However, there is evidence that some mRNAs are also localized to the ER independently of translation, suggesting that mRNA localization to the ER can be regulated.

In addition to the ER, RNA is found in other organelles. For example, certain lncRNAs are localized to the nucleus, where they regulate chromatin state. The nucleolus, as discussed, is a site of rRNA synthesis and ribosome assembly. RNA granules, such as stress granules and processing bodies (P-bodies), are cytoplasmic foci where mRNA is stored or degraded. Stress granules form under conditions of cellular stress and contain translationally stalled mRNAs, while P-bodies contain mRNAs targeted for degradation or translational repression.

## Methods to Study RNA Location

Determining where RNA is located within a cell requires methods that preserve spatial information. Several techniques are available, each with distinct strengths and limitations.

### Fluorescence [In Situ Hybridization](/knowledge/molecular-biology/in-situ-hybridization) (FISH)

Fluorescence [in situ hybridization](/knowledge/molecular-biology/in-situ-hybridization) (FISH) is the gold standard for visualizing RNA in fixed cells. In this method, cells are fixed and permeabilized, and a labeled probe complementary to the target RNA is hybridized to the sample. The probe can be labeled with a fluorophore directly or with a hapten (such as digoxigenin or biotin) that is detected by a fluorescently labeled antibody.

Single-molecule FISH (smFISH) uses multiple short probes (typically 20–50 nucleotides) each labeled with a single fluorophore. Because each mRNA is bound by many probes, the signal from a single mRNA is bright enough to be detected as a diffraction-limited spot. smFISH allows the quantification of individual mRNA molecules and their positions within the cell. For example, smFISH has been used to show that β-actin mRNA is enriched at the leading edge of migrating fibroblasts and that specific mRNAs are asymmetrically distributed in Drosophila embryos.

### Subcellular Fractionation and Sequencing

Subcellular fractionation separates cellular compartments by differential centrifugation or [density gradient centrifugation](/knowledge/molecular-biology/density-gradient-centrifugation), followed by RNA sequencing (RNA-seq) of each fraction. In a typical protocol, cells are lysed gently to preserve organelles, and the lysate is centrifuged at low speed (e.g., 1,000 × g for 10 minutes) to pellet nuclei. The supernatant is then centrifuged at higher speed (e.g., 15,000 × g for 15 minutes) to pellet mitochondria and other heavy organelles, and finally at 100,000 × g for 1 hour to pellet microsomes (ER-derived vesicles). RNA is extracted from each fraction and sequenced.

This approach provides a global view of RNA distribution across compartments but has limited spatial resolution. It cannot distinguish between different regions of the cytoplasm, for example. However, it is powerful for identifying transcripts that are enriched in specific compartments, such as nuclear-retained lncRNAs or ER-associated mRNAs.

### Live-Cell Imaging of RNA

Live-cell imaging allows the dynamics of RNA localization to be observed in real time. One approach uses the MS2 system, in which the RNA of interest is engineered to contain stem-loop sequences (MS2 binding sites) in its 3′ UTR. A fusion protein consisting of the MS2 coat protein and a fluorescent protein (such as GFP) binds to these stem-loops, allowing the RNA to be visualized. By expressing this system in cells, the movement of individual mRNA molecules can be tracked over time.

Another approach uses the CRISPR-Cas9 system to label endogenous RNA. In this method, a catalytically dead Cas9 (dCas9) is fused to a fluorescent protein and guided to the RNA of interest by a guide RNA complementary to the target. This allows the visualization of endogenous transcripts without modifying the RNA sequence.

Live-cell imaging has revealed that mRNA movement is not purely diffusive. Many mRNAs exhibit directed motion along microtubules, with velocities of 0.5–1.5 μm/s, consistent with motor-protein-driven transport. These observations have confirmed that active transport is a major mechanism of mRNA localization.

## Functional Implications of RNA Localization

RNA localization is not a curiosity; it is a fundamental mechanism that cells use to organize their functions. The most direct consequence is local protein synthesis, which allows proteins to be produced at their site of action. This is particularly important for proteins that are toxic or unstable if produced elsewhere, or for proteins that need to be produced rapidly in response to local signals.

Cellular asymmetry is another key function. In many cell types, the distribution of proteins is asymmetric, and this asymmetry often originates from asymmetric mRNA localization. In Drosophila, the localization of bicoid and oskar mRNAs to opposite poles of the embryo establishes the anterior-posterior axis. In budding yeast, the localization of ASH1 mRNA to the bud tip ensures that the daughter cell inherits a different transcriptional program than the mother cell. In neurons, the localization of mRNAs to dendrites allows synapses to be modified independently, which is the basis of synaptic plasticity and memory.

RNA localization also enables rapid responses to stimuli. When a cell receives a signal, it can immediately translate localized mRNAs without waiting for transcription and export. This is particularly important in neurons, where local translation at synapses allows the cell to respond to synaptic activity within minutes. Similarly, in migrating cells, localized translation of actin and actin-binding proteins at the leading edge allows the cell to respond quickly to chemotactic signals.

Finally, RNA localization can serve as a quality control mechanism. By retaining improperly processed or unneeded mRNAs in the nucleus, the cell prevents the production of aberrant proteins. Nuclear retention of certain mRNAs also allows the cell to regulate gene expression post-transcriptionally, by controlling when and whether an mRNA is exported.

## Common Pitfalls and Misconceptions in RNA Localization

Students often make several errors when learning about RNA localization. The most common is assuming that all RNA is in the cytoplasm. In fact, a substantial fraction of RNA is nuclear, including pre-mRNA, snRNA, snoRNA, and many lncRNAs. Even in the cytoplasm, RNA is not uniformly distributed; it is often localized to specific regions or organelles.

Another misconception is that mRNA is always translated immediately after export. In reality, many mRNAs are stored in a translationally repressed state, either in RNA granules or bound by repressive RBPs. Translation can be activated later, in response to specific signals. For example, maternal mRNAs in oocytes are often stored in a dormant state and translated only after fertilization.

A related error is assuming that all ribosomes are free in the cytoplasm. In fact, ribosomes synthesizing secretory or membrane proteins are bound to the ER membrane. The mRNA encoding these proteins is therefore localized to the ER, not free in the cytosol.

Students also sometimes confuse the mechanisms of RNA localization. It is important to distinguish between active transport (motor-protein-driven movement along cytoskeletal tracks), local entrapment (anchoring at a specific site), and protection from degradation. These mechanisms are not mutually exclusive; a single mRNA may use multiple mechanisms at different stages of its localization.

Finally, students may assume that RNA localization is static. In reality, RNA is highly dynamic. mRNAs can be transported, anchored, released, and re-localized in response to cellular signals. Live-cell imaging has shown that many mRNAs are in constant motion, even when their overall distribution appears stable.

## Summary and Key Takeaways

RNA location is the regulated subcellular distribution of RNA molecules, and it is essential for proper gene expression. Different RNA types have characteristic locations: mRNA is exported to the cytoplasm, tRNA shuttles between the cytoplasm and ribosomes, rRNA is synthesized in the nucleolus and functions in the cytoplasm, and non-coding RNAs are distributed according to their functions. Nuclear RNA localization is coupled to transcription and processing, with nuclear speckles and the nucleolus serving as specialized compartments. Cytoplasmic RNA localization is achieved by active transport, local entrapment, and protection from degradation, and it underlies cell polarity and local protein synthesis. RNA is also targeted to organelles, including mitochondria and the ER. Methods to study RNA location include FISH, subcellular fractionation with sequencing, and live-cell imaging. Understanding RNA location is critical for understanding development, neuronal function, and cellular responses to stimuli.

## Frequently Asked Questions

### What is RNA location?

RNA location is the subcellular distribution of RNA molecules—where specific transcripts are found within a cell. It is an actively regulated process that determines when and where proteins are synthesized, and it is essential for cellular function, polarity, and response to stimuli.

### What are the types of RNA and their locations?

The major types of RNA are mRNA (cytoplasm after export), tRNA (cytoplasm, with some imported into mitochondria), rRNA (nucleolus for synthesis, cytoplasm in ribosomes), snRNA (nucleus), snoRNA (nucleolus), miRNA (cytoplasm in RISC), lncRNA (nucleus or cytoplasm depending on the transcript), and piRNA (nucleus and cytoplasm in germ cells).

### Where is mRNA located in the cell?

mRNA is synthesized in the nucleus and exported to the cytoplasm. In the cytoplasm, it can be free in the cytosol, associated with ribosomes, or localized to specific regions such as the leading edge of migrating cells, dendrites of neurons, or the ER membrane for secretory proteins.

### Where is tRNA located?

tRNA is transcribed in the nucleus and exported to the cytoplasm, where it delivers amino acids to ribosomes. In some organisms, a subset of tRNAs is imported into mitochondria to support mitochondrial translation.

### Where is rRNA located?

rRNA is synthesized in the nucleolus, where it is processed and assembled with ribosomal proteins into subunits. The subunits are then exported to the cytoplasm, where they form functional ribosomes. Thus, rRNA is found in the nucleolus during synthesis and in the cytoplasm as part of ribosomes.

### Why is RNA location important?

RNA location is important because it enables local protein synthesis, establishes cellular asymmetry, allows rapid responses to stimuli, and serves as a quality control mechanism. By localizing mRNA, cells can produce proteins exactly where they are needed, without relying on protein diffusion.

### How is RNA location determined?

RNA location is determined by mechanisms such as active transport along the cytoskeleton, local entrapment by anchoring proteins, and protection from degradation in specific regions. These mechanisms are mediated by RNA-binding proteins that recognize localization elements in the RNA, typically in the 3′ UTR.

## Key Takeaways

- RNA location is actively regulated and essential for gene expression, cell polarity, and local protein synthesis.
- mRNA is exported to the cytoplasm, where it can be localized to specific regions; tRNA and rRNA have distinct nuclear and cytoplasmic distributions.
- Nuclear RNA localization is coupled to transcription and processing, with nuclear speckles and the nucleolus as key compartments.
- Cytoplasmic mRNA localization is achieved by active transport, local entrapment, and protection from degradation.
- RNA is targeted to organelles, including mitochondria (tRNA import) and the ER (mRNA encoding secretory proteins).
- Methods to study RNA location include FISH, subcellular fractionation with sequencing, and live-cell imaging.
- Common misconceptions include assuming all RNA is cytoplasmic, that mRNA is always translated immediately, and that RNA localization is static.

## Further Reading

- Kong LB et al. *RNA location and modeling of a WD40 repeat domain within the vault*. RNA (New York, N.Y.). 2000. [PubMed 10864046](https://doi.org/10.1017/s1355838200000157)
- Chen R et al. *CIN grades possessing different HPV RNA location patterns and RNAscope is helpful tool for distinguishing squamous intraepithelial lesions in difficult cervical cases*. Diagnostic pathology. 2023. [PubMed 36797728](https://doi.org/10.1186/s13000-023-01308-w)
- Subramaniam K et al. *The 3'-untranslated region length and AU-rich RNA location modulate RNA-protein interaction and translational control of β2-adrenergic receptor mRNA*. Molecular and cellular biochemistry. 2011. [PubMed 21369731](https://doi.org/10.1007/s11010-011-0747-z)
- Zhang SY et al. *A Modular Engineered DNA Nanodevice for Precise Profiling of Telomerase RNA Location and Activity*. Advanced science (Weinheim, Baden-Wurttemberg, Germany). 2025. [PubMed 39731326](https://doi.org/10.1002/advs.202409344)
- Tee MK et al. *A promoter within intron 35 of the human C4A gene initiates abundant adrenal-specific transcription of a 1 kb RNA: location of a cryptic CYP21 promoter element?*. Human molecular genetics. 1995. [PubMed 8589688](https://doi.org/10.1093/hmg/4.11.2109)
- Croall DE, Morrison MR. *Polysomal and non-polysomal messenger RNA in neuroblastoma cells. Lack of correlation between polyadenylation or initiation efficiency and messenger RNA location*. Journal of molecular biology. 1980. [PubMed 7431399](https://doi.org/10.1016/0022-2836(80)90270-3)

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* [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)