Phosphorylation of the human cell proliferation-associated nucleolar protein p120.
The human cell proliferation-associated nucleolar protein p120 was found in a variety of human cancer specimens but not in most normal resting cells. Polyclonal antibodies raised against bacterially expressed p120 were used to immunoprecipitate the p120 protein isolated from 32P-labeled HeLa cells. The p120 protein was phosphorylated at serine, threonine and tyrosine residues. A tryptic peptide map showed it contained three labeled peptides. One of these peptides comigrated with a p120 peptide phosphorylated in vitro by casein kinase II. This peptide was phosphorylated in vitro both at Ser-181 and Thr-185. This region is juxtaposed to the epitope site recognized by the anti-p120 monoclonal antibody.
Valdez
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BC
Department of Pharmacology, Baylor College of Medicine, Houston, Texas 77030.
Busch
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RK
Busch
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H
D000595:Amino Acid Sequence; D000596:Amino Acids / Q000032:analysis; D002352:Carrier Proteins / Q000235:genetics / Q000302:isolation & purification; D003001:Cloning, Molecular; D006367:HeLa Cells / Q000378:metabolism; D006801:Humans; D058619:Maltose-Binding Proteins; D008969:Molecular Sequence Data; D009687:Nuclear Proteins / Q000235:genetics / Q000276:immunology / Q000302:isolation & purification / Q000378:metabolism*; D010446:Peptide Fragments / Q000302:isolation & purification; D010766:Phosphorylation; D015183:Restriction Mapping; D014357:Trypsin; D012359:tRNA Methyltransferases
D000596:Amino Acids; D002352:Carrier Proteins; D058619:Maltose-Binding Proteins; D009687:Nuclear Proteins; D010446:Peptide Fragments; C065028:NOP2 protein, human; D012359:tRNA Methyltransferases; D014357:Trypsin