The yeast Pan2 protein is required for poly(A)-binding protein-stimulated poly(A)-nuclease activity.
The removal of the mRNA poly(A) tail in the yeast Saccharomyces cerevisiae is stimulated by the poly(A)-binding protein (Pab1p). A large scale purification of the Pab1p-stimulated poly(A) ribonuclease (PAN) identifies a 76-kDa and two 135-Da polypeptides as candidate enzyme subunits. Antibodies against the Pan1p protein, which is the minor 135-kDa protein in the preparation, can immunodeplete Pan1p but not PAN activity. The protein sequence of the major 135-kDa protein, Pan2p, reveals a novel protein that was also found in the previously reported PAN purification (Sachs, A. B., and Deardorff, J. A. (1992) Cell 70, 961-973). Deletion of the non-essential PAN2 gene results in an increase of the average length of mRNA poly(A) tails in vivo, and a loss of Pab1p-stimulated PAN activity in crude extracts. These data confirm that Pan2p and not Pan1p is required for PAN activity, and they suggest that ribonucleases other than the Pab1p-stimulated PAN are capable of shortening poly(A) tails in vivo.
Department of Molecular and Cell Biology, University of California at Berkeley 94720, USA.
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Boeck
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Tarun
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Rieger
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Deardorff
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Müller-Auer
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Sachs
D000595:Amino Acid Sequence; D001483:Base Sequence; D002470:Cell Survival; D017931:DNA Primers; D005095:Exoribonucleases / Q000378:metabolism*; D016681:Genome, Fungal; D008969:Molecular Sequence Data; D016296:Mutagenesis; D039102:Poly(A)-Binding Proteins; D016601:RNA-Binding Proteins / Q000378:metabolism*; D018160:Receptors, Cytoplasmic and Nuclear / Q000378:metabolism*; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000378:metabolism*
D017931:DNA Primers; D005095:Exoribonucleases; D039102:Poly(A)-Binding Proteins; D016601:RNA-Binding Proteins; D018160:Receptors, Cytoplasmic and Nuclear