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 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.
Kreivi
J P
JP
Medical Immunology and Microbiology, BMC, Uppsala University, Sweden. Jan-Peter.Kreivi@imim.uu.se
Trinkle-Mulcahy
L
L
Lyon
C E
CE
Morrice
N A
NA
Cohen
P
P
Lamond
A I
AI
D000595:Amino Acid Sequence; D002457:Cell Extracts; D002466:Cell Nucleolus / Q000737:chemistry; D002467:Cell Nucleus / Q000737:chemistry; D017124:Conserved Sequence; D004268:DNA-Binding Proteins; D015870:Gene Expression; D006367:HeLa Cells; D006801:Humans; D008969:Molecular Sequence Data; D008970:Molecular Weight; D009687:Nuclear Proteins / Q000235:genetics / Q000302:isolation & purification* / Q000378:metabolism*; D009928:Organ Specificity; D010749:Phosphoprotein Phosphatases / Q000378:metabolism*; D011485:Protein Binding; D054645:Protein Phosphatase 1; D012333:RNA, Messenger / Q000032:analysis; D016601:RNA-Binding Proteins / Q000235:genetics; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D016335:Zinc Fingers
D002457:Cell Extracts; D004268:DNA-Binding Proteins; D009687:Nuclear Proteins; C110225:PPP1R10 protein, human; D012333:RNA, Messenger; D016601:RNA-Binding Proteins; D011993:Recombinant Fusion Proteins; D010749:Phosphoprotein Phosphatases; D054645:Protein Phosphatase 1