Molecular cloning of NIPP-1, a nuclear inhibitor of protein phosphatase-1, reveals homology with polypeptides involved in RNA processing.
NIPP-1 was originally isolated as a potent and specific nuclear inhibitory polypeptide (16-18 kDa) of protein phosphatase-1. We report here the cDNA cloning of NIPP-1 from bovine thymus and show that the native polypeptide consists of 351 residues and has a calculated mass of 38.5 kDa. The bacterially expressed central third of NIPP-1 completely inhibited the type-1 catalytic subunit, but displayed a reduced inhibitory potency after phosphorylation by protein kinase A and casein kinase 2. Translation of NIPP-1 mRNA in reticulocyte lysates resulted in the accumulation of both intact NIPP-1 and a smaller polypeptide generated by alternative initiation at the codon corresponding to Met143. A data base search showed that the COOH terminus of NIPP-1 is nearly identical to the human ard-1 protein (13 kDa), which has been implicated in RNA processing (Wang, M., and Cohen, S. N. (1994) Proc. Natl. Acad. Sci. U. S. A. 91, 10591-10595). Comparison of the cDNAs encoding ard-1 and NIPP-1 suggests that their mRNAs are generated by alternative splicing of the same pre-mRNA. Western blotting with antibodies against the COOH terminus of NIPP-1, however, showed a single polypeptide of 47 kDa, which was enriched in the nucleus. Northern analysis revealed a single transcript of 2.2 kilobases in bovine thymus and of 2.4 kilobases in various human tissues.
D017398:Alternative Splicing; D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D002352:Carrier Proteins; D002417:Cattle; D003001:Cloning, Molecular; D017931:DNA Primers; D018076:DNA, Complementary; D004722:Endoribonucleases / Q000096:biosynthesis / Q000737:chemistry*; D015723:Gene Library; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins; D008099:Liver / Q000378:metabolism; D008969:Molecular Sequence Data; D008970:Molecular Weight; D009838:Oligodeoxyribonucleotides; D009928:Organ Specificity; D010749:Phosphoprotein Phosphatases / Q000037:antagonists & inhibitors; D016133:Polymerase Chain Reaction; D014176:Protein Biosynthesis; D054645:Protein Phosphatase 1; D011506:Proteins / Q000737:chemistry* / Q000302:isolation & purification; D012323:RNA Processing, Post-Transcriptional; D012333:RNA, Messenger / Q000096:biosynthesis; D016601:RNA-Binding Proteins; D011994:Recombinant Proteins / Q000096:biosynthesis / Q000737:chemistry; D017386:Sequence Homology, Amino Acid; D013950:Thymus Gland / Q000378:metabolism*
D002352:Carrier Proteins; D017931:DNA Primers; D018076:DNA, Complementary; D047908:Intracellular Signaling Peptides and Proteins; D009838:Oligodeoxyribonucleotides; D011506:Proteins; D012333:RNA, Messenger; D016601:RNA-Binding Proteins; D011994:Recombinant Proteins; C021042:protein phosphatase inhibitor-1; D004722:Endoribonucleases; D010749:Phosphoprotein Phosphatases; D054645:Protein Phosphatase 1; C097081:PPP1R8 protein, human