PUB1: a major yeast poly(A)+ RNA-binding protein.
The expression of RNA polymerase II transcripts can be regulated at the posttranscriptional level by RNA-binding proteins. Although extensively characterized in metazoans, relatively few RNA-binding proteins have been characterized in the yeast Saccharomyces cerevisiae. Three major proteins are cross-linked by UV light to poly(A)+ RNA in living S. cerevisiae cells. These are the 72-kDa poly(A)-binding protein and proteins of 60 and 50 kDa (S.A. Adam, T.Y. Nakagawa, M.S. Swanson, T. Woodruff, and G. Dreyfuss, Mol. Cell. Biol. 6:2932-2943, 1986). Here, we describe the 60-kDa protein, one of the major poly(A)+ RNA-binding proteins in S. cerevisiae. This protein, PUB1 [for poly(U)-binding protein 1], was purified by affinity chromatography on immobilized poly(rU), and specific monoclonal antibodies to it were produced. UV cross-linking demonstrated that PUB1 is bound to poly(A)+ RNA (mRNA or pre-mRNA) in living cells, and it was detected primarily in the cytoplasm by indirect immunofluorescence. The gene for PUB1 was cloned and sequenced, and the sequence was found to predict a 51-kDa protein with three ribonucleoprotein consensus RNA-binding domains and three glutamine- and asparagine-rich auxiliary domains. This overall structure is remarkably similar to the structures of the Drosophila melanogaster elav gene product, the human neuronal antigen HuD, and the cytolytic lymphocyte protein TIA-1. Each of these proteins has an important role in development and differentiation, potentially by affecting RNA processing. PUB1 was found to be nonessential in S. cerevisiae by gene replacement; however, further genetic analysis should reveal important features of this class of RNA-binding proteins.
Matunis
M J
MJ
Howard Hughes Medical Institute, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania 19104-6148.
Matunis
E L
EL
Dreyfuss
G
G
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D003001:Cloning, Molecular; D004271:DNA, Fungal; D004331:Drosophila melanogaster; D005455:Fluorescent Antibody Technique; D005656:Fungal Proteins / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D006801:Humans; D015151:Immunoblotting; D008969:Molecular Sequence Data; D039102:Poly(A)-Binding Proteins; D011233:Precipitin Tests; D012331:RNA, Fungal / Q000378:metabolism; D016601:RNA-Binding Proteins / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins
D004271:DNA, Fungal; D005656:Fungal Proteins; C083327:PUB1 protein, S cerevisiae; D039102:Poly(A)-Binding Proteins; D012331:RNA, Fungal; D016601:RNA-Binding Proteins; D029701:Saccharomyces cerevisiae Proteins