Involved in the packaging of pre-mRNA into hnRNP particles, transport of poly(A) mRNA from the nucleus to the cytoplasm and modulation of splice site selection (PubMed:17371836). 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). Binds to the IRES and thereby inhibits the translation of the apoptosis protease activating factor APAF1 (PubMed:31498791). May bind to specific miRNA hairpins (PubMed:28431233). (Microbial infection) May play a role in HCV RNA replication. (Microbial infection) Cleavage by Enterovirus 71 protease 3C results in increased translation of apoptosis protease activating factor APAF1, leading to apoptosis. Identified in the spliceosome C complex (PubMed:11991638). Identified in a IGF2BP1-dependent mRNP granule complex containing untranslated mRNAs (PubMed:17289661). Interacts with SEPT6 (PubMed:17229681). Interacts with C9orf72 (PubMed:24549040). Interacts with KHDRBS1 (PubMed:17371836). Interacts with UBQLN2 (PubMed:25616961). Interacts with PPIA/CYPA (PubMed:25678563). Interacts (via the RGG-box) with the HOXB-AS3 peptide; the interaction inhibits binding of HNRNPA1 to the intronic sequences flanking exon 9 of the PKM gene, preventing inclusion of exon 9 and promoting inclusion of exon 10 which suppresses formation of the PKM M2 isoform and promotes production of the M1 isoform (PubMed:28985503). (Microbial infection) Interacts with HCV NS5B and with the 5'-UTR and 3'-UTR of HCV RNA. (Microbial infection) May interact with SARS-CoV Nucleoprotein. Localized in cytoplasmic mRNP granules containing untranslated mRNAs. Shuttles continuously between the nucleus and the cytoplasm along with mRNA. Component of ribonucleosomes (PubMed:17289661). (Microbial infection) In the course of viral infection, colocalizes with HCV NS5B at speckles in the cytoplasm in a HCV-replication dependent manner. (Microbial infection) SARS coronavirus-2/SARS-CoV-2 ORF6 protein increases accumulation to the nucleus. Arg-194, Arg-206 and Arg-225 are dimethylated, probably to asymmetric dimethylarginine. Sumoylated. The disease is caused by variants affecting the gene represented in this entry. The disease is caused by variants affecting the gene represented in this entry. Is twenty times more abundant than isoform A1-B. Variant Val-314 has been originally associated with IBMPFD3 and variant Asn-314 with ALS20 (PubMed:25616961). However in another report, variant Val-314 is associated with amyotrophic lateral sclerosis (ALS) but this variant is not supported by clinical data in this publication (PubMed:25616961).