Yeast NPI46 encodes a novel prolyl cis-trans isomerase that is located in the nucleolus.
We have identified a gene (NPI46) encoding a new prolyl cis-trans isomerase within the nucleolus of the yeast Saccharomyces cerevisiae. The protein encoded by NPI46 was originally found by us in a search for proteins that recognize nuclear localization sequences (NLSs) in vitro. Thus, NPI46 binds to affinity columns that contain a wild-type histone H2B NLS but not a mutant H2B NLS that is incompetent for nuclear localization in vivo. NPI46 has two domains, a highly charged NH2 terminus similar to two other mammalian nucleolar proteins, nucleolin and Nopp140, and a COOH terminus with 45% homology to a family of mammalian and yeast proline isomerases. NPI46 is capable of catalyzing the prolyl cis-trans isomerization of two small synthetic peptides, succinyl-Ala-Leu-Pro-Phe-p-nitroanilide and succinyl-Ala-Ala-Pro-Phe-p-nitroanilide, as measured by a chymotrypsin-coupled spectrophotometric assay. By indirect immunofluorescence we have shown that NPI46 is a nucleolar protein. NPI46 is not essential for cell viability.
Shan
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Department of Biological Sciences, Columbia University, New York 10027.
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Mélèse
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D000591:Amino Acid Isomerases / Q000096:biosynthesis* / Q000235:genetics / Q000302:isolation & purification; D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D002352:Carrier Proteins / Q000096:biosynthesis* / Q000235:genetics / Q000302:isolation & purification; D002466:Cell Nucleolus / Q000201:enzymology*; D002846:Chromatography, Affinity; D003001:Cloning, Molecular; D004271:DNA, Fungal / Q000302:isolation & purification / Q000378:metabolism; D004926:Escherichia coli; D005800:Genes, Fungal; D007700:Kinetics; D008322:Mammals; D051379:Mice; D008969:Molecular Sequence Data; D009842:Oligopeptides / Q000378:metabolism; D019696:Peptidylprolyl Isomerase; D010957:Plasmids; D011994:Recombinant Proteins / Q000096:biosynthesis / Q000302:isolation & purification / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000201:enzymology* / Q000235:genetics*; D017386:Sequence Homology, Amino Acid; D013379:Substrate Specificity
D002352:Carrier Proteins; D004271:DNA, Fungal; D009842:Oligopeptides; D011994:Recombinant Proteins; D000591:Amino Acid Isomerases; D019696:Peptidylprolyl Isomerase