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Purification and characterisation of p99, a nuclear modulator of protein phosphatase 1 activity

We have purified a form of protein phosphatase 1 (PP1) from HeLa cell nuclei, in which the phosphatase is complexed to a regulatory subunit termed p99. We report here the cloning and characterisation of the p99 component. p99 mRNA is widely expressed in human tissues and immunofluorescence analysis...

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Bibliographic Details
Published in:FEBS letters 1997-12, Vol.420 (1), p.57-62
Main Authors: Kreivi, Jan-Peter, Trinkle-Mulcahy, Laura, Lyon, Carol E, Morrice, Nick A, Cohen, Philip, Lamond, Angus I
Format: Article
Language:English
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Summary:We have purified a form of protein phosphatase 1 (PP1) from HeLa cell nuclei, in which the phosphatase is complexed to a regulatory subunit termed p99. We report here the cloning and characterisation of the p99 component. p99 mRNA is widely expressed in human tissues and immunofluorescence analysis with anti-p99 antibodies showed a punctate nucleoplasmic staining with additional accumulations within the nucleolus. The C-terminus of p99 contains seven RGG RNA-binding motifs, followed by eleven decapeptide repeats containing six or more of the following conserved residues (GHRPHEGPGG), and finally a putative zinc finger domain. Recombinant p99 suppresses the phosphorylase phosphatase activity of PP1 by >90% and the canonical PP1-binding motif on p99 (residues 396–401) is unusual in that the phenylalanine residue is replaced by tryptophan.
ISSN:0014-5793
1873-3468
DOI:10.1016/S0014-5793(97)01485-3