Protein: Polyadenylate-binding protein, cytoplasmic and nuclear (PABP) (Poly(A)-binding protein) (ARS consensus-binding protein ACBP-67) (Polyadenylate tail-binding protein) (P04147)
Organism: Saccharomyces cerevisiae (strain ATCC 204508 / S288c) (Baker's yeast)
Function: Binds the poly(A) tail of mRNA. Appears to be an important mediator of the multiple roles of the poly(A) tail in mRNA biogenesis, stability and translation. In the nucleus, interacts with the nuclear cleavage factor IA (CFIA), which is required for both mRNA cleavage and polyadenylation. Is also required for efficient mRNA export to the cytoplasm. Acts in concert with a poly(A)-specific nuclease (PAN) to affect poly(A) tail shortening, which may occur concomitantly with either nucleocytoplasmic mRNA transport or translational initiation. Regulates PAN activity via interaction with the stimulator PAN3 or the inhibitor PBP1. In the cytoplasm, affects both translation and mRNA decay. Stimulates translation by interaction with translation initiation factor eIF4G, a subunit of the cap-binding complex eIF4F, bringing the 5'- and 3'-ends of the mRNA in proximity. The formation of this circular mRNP structure appears to be critical for the synergistic effects of the cap and the poly(A) tail in facilitating translation initiation, recycling of ribosomes, and mRNA stability. Also regulates translation termination by recruiting eukaryotic release factor 3 (eRF3). Interaction with eRF3 is also required for regulation of normal mRNA decay through translation termination-coupled poly(A) shortening, probably mediated by PAN. Loss of PAB1 from the mRNP after deadenylation triggers mRNA degradation. Inhibits the major cytoplasmic mRNA deadenylase CCR4-NOT complex. Is also associated peripherally with COPI vesicles through its interaction with ARF1, and this is required for correct localization of the asymmetrically distributed ASH1 mRNA.
Subcellular location: Cytoplasm. Nucleus. Note=Predominantly cytoplasmic. Rapidly shuttles between the nucleus and the cytoplasm. Can be exported from the nucleus through at least 2 distinct pathways, the main being dependent on the exportin CRM1, and the second requiring MEX67 and ongoing mRNA export. Import is mediated by the importin SXM1.
Interaction partners:
- Eukaryotic initiation factor 4F subunit p150
- Eukaryotic translation initiation factor 4E
- Eukaryotic initiation factor 4F subunit p130
- Eukaryotic peptide chain release factor GTP-binding subunit
- PAB1-binding protein 1
- ATP-dependent RNA helicase eIF4A
- U1 small nuclear ribonucleoprotein A
- PAN2-PAN3 deadenylation complex subunit PAN3
- Nucleolar complex protein 2
- Protein NAM8
Sequence:
MADITDKTAEQLENLNIQDDQKQAATGSESQSVENSSASLYVGDLEPSVSEAHLYDIFSPIGSVSSIRVCRDAITKTSLGYAYVNFNDHEAGRKAIEQLNYTPIKGRLCRIMWSQRDPSLRKKGSGNIFIKNLHPDIDNKALYDTFSVFGDILSSKIATDENGKSKGFGFVHFEEEGAAKEAIDALNGMLLNGQEIYVAPHLSRKERDSQLEETKAHYTNLYVKNINSETTDEQFQELFAKFGPIVSASLEKDADGKLKGFGFVNYEKHEDAVKAVEALNDSELNGEKLYVGRAQKKNERMHVLKKQYEAYRLEKMAKYQGVNLFVKNLDDSVDDEKLEEEFAPYGTITSAKVMRTENGKSKGFGFVCFSTPEEATKAITEKNQQIVAGKPLYVAIAQRKDVRRSQLAQQIQARNQMRYQQATAAAAAAAAGMPGQFMPPMFYGVMPPRGVPFNGPNPQQMNPMGGMPKNGMPPQFRNGPVYGVPPQGGFPRNANDNNQFYQQKQRQALGEQLYKKVSAKTSNEEAAGKITGMILDLPPQEVFPLLESDELFEQHYKEASAAYESFKKEQEQQTEQA