HNRNPA2B1
Domain
The disordered region, when incubated at high concentration, is able to polymerize into labile, amyloid-like fibers and form cross-beta polymerization structures, probably driving the formation of hydrogels. In contrast to irreversible, pathogenic amyloids, the fibers polymerized from low complexity (LC) regions disassemble upon dilution. A number of evidence suggests that formation of cross-beta structures by LC regions mediate the formation of RNA granules, liquid-like droplets, and hydrogels.
Function
Heterogeneous nuclear ribonucleoprotein (hnRNP) that associates with nascent pre-mRNAs, packaging them into hnRNP particles. The hnRNP particle arrangement on nascent hnRNA is non-random and sequence-dependent and serves to condense and stabilize the transcripts and minimize tangling and knotting. Packaging plays a role in various processes such as transcription, pre-mRNA processing, RNA nuclear export, subcellular location, mRNA translation and stability of mature mRNAs (PubMed:19099192). Forms hnRNP particles with at least 20 other different hnRNP and heterogeneous nuclear RNA in the nucleus. Involved in transport of specific mRNAs to the cytoplasm in oligodendrocytes and neurons: acts by specifically recognizing and binding the A2RE (21 nucleotide hnRNP A2 response element) or the A2RE11 (derivative 11 nucleotide oligonucleotide) sequence motifs present on some mRNAs, and promotes their transport to the cytoplasm (PubMed:10567417). Specifically binds single-stranded telomeric DNA sequences, protecting telomeric DNA repeat against endonuclease digestion (By similarity). Also binds other RNA molecules, such as primary miRNA (pri-miRNAs): acts as a nuclear 'reader' of the N6-methyladenosine (m6A) mark by specifically recognizing and binding a subset of nuclear m6A-containing pri-miRNAs. Binding to m6A-containing pri-miRNAs promotes pri-miRNA processing by enhancing binding of DGCR8 to pri-miRNA transcripts (PubMed:26321680). Involved in miRNA sorting into exosomes following sumoylation, possibly by binding (m6A)-containing pre-miRNAs (PubMed:24356509). Acts as a regulator of efficiency of mRNA splicing, possibly by binding to m6A-containing pre-mRNAs (PubMed:26321680). Plays a role in the splicing of pyruvate kinase PKM by binding repressively to sequences flanking PKM exon 9, inhibiting exon 9 inclusion and resulting in exon 10 inclusion and production of the PKM M2 isoform (PubMed:20010808). Also plays a role in the activation of the innate immune response (PubMed:31320558). Mechanistically, senses the presence of viral DNA in the nucleus, homodimerizes and is demethylated by JMJD6 (PubMed:31320558). In turn, translocates to the cytoplasm where it activates the TBK1-IRF3 pathway, leading to interferon alpha/beta production (PubMed:31320558).
(Microbial infection) Involved in the transport of HIV-1 genomic RNA out of the nucleus, to the microtubule organizing center (MTOC), and then from the MTOC to the cytoplasm: acts by specifically recognizing and binding the A2RE (21 nucleotide hnRNP A2 response element) sequence motifs present on HIV-1 genomic RNA, and promotes its transport.
Involvement in disease
Inclusion body myopathy with early-onset Paget disease with or without frontotemporal dementia 2
IBMPFD2
An autosomal dominant disease characterized by disabling muscle weakness clinically resembling to limb girdle muscular dystrophy, osteolytic bone lesions consistent with Paget disease, and premature frontotemporal dementia. Clinical features show incomplete penetrance.
None
The disease is caused by variants affecting the gene represented in this entry.
Oculopharyngeal muscular dystrophy 2
OPMD2
An autosomal dominant, early-onset myopathy characterized by progressive muscle weakness, ptosis, ophthalmoplegia, dysphagia, and variable degrees of respiratory insufficiency.
None
The disease is caused by variants affecting the gene represented in this entry. The disease is caused by frameshift variants that cluster in the low complexity disordered region. They abolish the native stop codon, and extend the reading frame resulting in a common C-terminal sequence. All variants escape degradation by the RNA quality control system, and mutant proteins accumulate in the cytoplasm due to impaired nucleocytoplasmic trafficking.
Post-translational modifications
Sumoylated in exosomes, promoting miRNAs-binding.
Asymmetric dimethylation at Arg-266 constitutes the major methylation site (By similarity). According to a report, methylation affects subcellular location and promotes nuclear localization (PubMed:10772824). According to another report, methylation at Arg-266 does not influence nucleocytoplasmic shuttling (By similarity).
Cellular localization
- Nucleus
- Nucleus
- Nucleoplasm
- Cytoplasm
- Cytoplasmic granule
- Secreted
- Extracellular exosome
- Localized in cytoplasmic mRNP granules containing untranslated mRNAs (PubMed:17289661). Component of ribonucleosomes (PubMed:17289661). Not found in the nucleolus (PubMed:17289661). Found in exosomes following sumoylation (PubMed:24356509).
- Isoform A2
- Nucleus
- Cytoplasm
- Predominantly nucleoplasmic, however is also found in the cytoplasm of cells in some tissues (PubMed:17289661).
Alternative names
HNRPA2B1, HNRNPA2B1, Heterogeneous nuclear ribonucleoproteins A2/B1, hnRNP A2/B1