Poly(A)-binding proteins (PABPs) bind to the poly(A) tail present at the 3-prime ends of most eukaryotic mRNAs. PABPC4 or IPABP (inducible PABP) was isolated as an activation-induced T-cell mRNA encoding a protein. Activation of T cells increased PABPC4 mRNA levels in T cells approximately 5-fold. PABPC4 contains 4 RNA-binding domains and proline-rich C terminus. PABPC4 is localized primarily to the cytoplasm. It is suggested that PABPC4 might be necessary for regulation of stability of labile mRNA species in activated T cells. PABPC4 was also identified as an antigen, APP1 (activated-platelet protein-1), expressed on thrombin-activated rabbit platelets. PABPC4 may also be involved in the regulation of protein translation in platelets and megakaryocytes or may participate in the binding or stabilization of polyadenylates in platelet dense granules. Alternatively spliced transcript variants encoding different isoforms have been found for this gene. [provided by RefSeq, Oct 2008]
Function:
Binds the poly(A) tail of mRNA. May be involved in cytoplasmic regulatory processes of mRNA metabolism. Can probably bind to cytoplasmic RNA sequences other than poly(A) in vivo.
Subunit:
Identified in a IGF2BP1-dependent mRNP granule complex containing untranslated mRNAs. Interacts with NFX1.
Subcellular Location:
Cytoplasm. Localized in cytoplasmic mRNP granules containing untranslated mRNAs.
Tissue Specificity:
Expressed at low levels in resting normal T cells; following T-cell activation, however, mRNA levels are rapidly up-regulated.
Post-translational modifications:
Arg-518 is dimethylated, probably to asymmetric dimethylarginine.
Similarity:
Belongs to the polyadenylate-binding protein type-1 family.
Contains 1 PABC domain.
Contains 4 RRM (RNA recognition motif) domains.
SWISS:
Q13310
Gene ID:
8761
Database links:
Entrez Gene: 8761 Human
Entrez Gene: 230721 Mouse
Entrez Gene: 298510 Rat
Omim: 603407 Human
SwissProt: Q13310 Human
Unigene: 169900 Human
Unigene: 277091 Mouse
Unigene: 201330 Rat
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