title: Phosphorylation and proteolytic degradation of nucleolin from 3T3-F442A cells.
abstract: The effect of phosphorylation on the proteolysis of nucleolin has been investigated. Nucleolin is readily phosphorylated both in vitro and in vivo. Utilizing phosphorylation assays and immunoblotting with anti-nucleolin serum, we have observed that phosphorylation enhances nucleolin as a substrate for a protease. This protease activity cleaves the protein into a highly phosphorylated 30 kDa peptide and a 72 kDa peptide. The involvement of casein kinase II is suggested since this cleavage is promoted by spermine and inhibited by heparin, which are, respectively, a stimulator and an inhibitor of casein kinase II activity. The molecular identity of the protease and the physiologic significance of the proteolytic cleavage of nucleolin remain to be studied.
authors.affiliation: Department of Biochemistry and Molecular Biology, State University of New York Health Science Center, Syracuse 13210.
authors.forename: P
authors.initials: P
authors.lastname: Warrener
authors.forename: R
authors.initials: R
authors.lastname: Petryshyn
mesh_terms: D016475:3T3 Cells; D000818:Animals; D047388:Casein Kinases; D010450:Endopeptidases / Q000378:metabolism*; D006493:Heparin / Q000494:pharmacology; D015151:Immunoblotting; D007700:Kinetics; D051379:Mice; D008970:Molecular Weight; D009687:Nuclear Proteins / Q000302:isolation & purification / Q000378:metabolism*; D010748:Phosphopeptides / Q000032:analysis; D010750:Phosphoproteins / Q000302:isolation & purification / Q000378:metabolism*; D010766:Phosphorylation; D011188:Potassium / Q000494:pharmacology; D011494:Protein Kinases / Q000378:metabolism*; D016601:RNA-Binding Proteins; D012964:Sodium / Q000494:pharmacology; D013096:Spermine / Q000494:pharmacology; D000097796:Nucleolin
chemical_list: D047388:Casein Kinases; D010450:Endopeptidases; D006493:Heparin; D009687:Nuclear Proteins; D010748:Phosphopeptides; D010750:Phosphoproteins; D011188:Potassium; D011494:Protein Kinases; D016601:RNA-Binding Proteins; D012964:Sodium; D013096:Spermine; D000097796:Nucleolin