The Xenopus laevis poly(A) binding protein is composed of multiple functionally independent RNA binding domains.
A family of eukaryotic RNA binding proteins is defined by the conserved RNP motif. The poly(A) binding protein has four such motifs. We report on the isolation and structural characterization of several variant cDNA clones, as well as of a gene encoding this protein in Xenopus laevis embryos. Wild-type protein as well as truncated versions carrying isolated single motifs or artificial combinations of two and more such elements were characterized for their ability to bind specifically to RNA homopolymers. Three of the isolated repeats were functional in specific RNA binding, whereas the N-terminal RNP motif was non-functional. Combinatorial effects in RNA binding were measured with constructs carrying multiple repeats, which were not predictable from the activity of isolated domains.
Max-Planck-Institut fuer Molekulare Genetik, Berlin, FRG.
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Nietfeld
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Mentzel
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Pieler
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D001665:Binding Sites; D002352:Carrier Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D003001:Cloning, Molecular; D004247:DNA / Q000235:genetics; D004252:DNA Mutational Analysis; D005796:Genes; D008969:Molecular Sequence Data; D015394:Molecular Structure; D011061:Poly A / Q000378:metabolism*; D039102:Poly(A)-Binding Proteins; D012333:RNA, Messenger / Q000378:metabolism*; D015183:Restriction Mapping; D014982:Xenopus laevis
D002352:Carrier Proteins; D039102:Poly(A)-Binding Proteins; D012333:RNA, Messenger; D011061:Poly A; D004247:DNA