A novel poly(A)-binding protein acts as a specificity factor in the second phase of messenger RNA polyadenylation.
Polyadenylation of mRNA precursors by poly(A) polymerase depends on a specificity factor, CPF, recognizing the polyadenylation signal AAUAAA. This paper describes an apparently novel poly(A)-binding protein that acts as a second specificity factor, mediating the recognition of the growing poly(A) tail. A transition from a slow initiation phase of polyadenylation to rapid elongation occurs when the growing tail is long enough to serve as a binding site for the poly(A)-binding protein. Elongation of an RNA carrying a tail of 10 or more adenylate residues can occur independently of CPF. A sharp decrease in the poly(A) chain growth rate after the addition of approximately 200 adenylate residues invites speculations about a role of the poly(A)-binding protein in poly(A) tail length control.
Wahle
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Department of Cell Biology, Biozentrum, Universität Basel, Switzerland.
D000818:Animals; D002352:Carrier Proteins / Q000737:chemistry / Q000378:metabolism*; D002417:Cattle; D066298:In Vitro Techniques; D011061:Poly A / Q000378:metabolism*; D039102:Poly(A)-Binding Proteins; D012322:RNA Precursors / Q000378:metabolism*; D012323:RNA Processing, Post-Transcriptional; D012333:RNA, Messenger / Q000378:metabolism*
D002352:Carrier Proteins; D039102:Poly(A)-Binding Proteins; D012322:RNA Precursors; D012333:RNA, Messenger; D011061:Poly A