skip to main content

Title: Platelet-derived growth factor induces phosphorylation of a 64-kDa nuclear protein

The platelet-derived growth factor (PDGF) stimulated the phosphorylation of a nuclear protein of 64 kDa (pp64) in nuclei of nontransformed normal rat kidney (NRK) cells. Low levels of phosphorylation of pp64 were observed in nuclei of serum-starved NRK cells. Fetal calf serum (FCS), PDGF, and homodimeric v-sis and PDGF A-chain protein enhanced the incorporation of 32P into pp64 over 4-fold within 30 min and over 8-fold within 2 h of exposure of NRK cells to the growth factors. In contrast, constitutive phosphorylation of 32P-labeled pp64 in nuclei of NRK cells transformed by the simian sarcoma virus (SSV) was high and only minimally stimulated by PDGF and FCS. 32P-Labeled pp64 was isolated from nuclei of PDGF-stimulated nontransformed NRK cells; the 32P of pp64 was labile in 1 M KOH, and pp64 was not significantly recognized by anti-phosphotyrosine antisera, suggesting that the PDGF-induced phosphorylation of pp64 occurred on serine or on threonine residues. However, pp64 from SSV-transformed NRK cell nuclei was significantly stable to base hydrolysis and was immunoprecipitated with anti-phosphotyrosine antisera, suggesting that pp64 from SSV-transformed cell nuclei is phosphorylated also on tyrosine. FCS, PDGF, and PDGF A- and B-chain homodimers thus stimulate the rapid time-dependent phosphorylation of a 64-kDa nuclearmore » protein shortly after stimulation of responsive cells. The growth factor-stimulated phosphorylation of pp64 and the constitutive high levels of pp64 phosphorylation in cells transformed by SSV suggest important roles for pp64 and perhaps regulated nuclear protein kinases and phosphatases in cell division and proliferation.« less
Authors:
; ; ;
Publication Date:
OSTI Identifier:
6354426
Resource Type:
Journal Article
Resource Relation:
Journal Name: J. Biol. Chem.; (United States); Journal Volume: 264:2
Research Org:
Jewish Hospital at Washington Univ. Medical Center, St. Louis, MO (USA)
Country of Publication:
United States
Language:
English
Subject:
59 BASIC BIOLOGICAL SCIENCES; GROWTH FACTORS; BIOLOGICAL FUNCTIONS; PHOSPHOPROTEINS; PHOSPHORYLATION; BLOOD COAGULATION FACTORS; CELL NUCLEI; CELL TRANSFORMATIONS; KIDNEYS; PHOSPHATASES; PHOSPHATES; PHOSPHORUS 32; PHOSPHOTRANSFERASES; RATS; TIME DEPENDENCE; TRACER TECHNIQUES; TYROSINE; AMINO ACIDS; ANIMALS; BETA DECAY RADIOISOTOPES; BETA-MINUS DECAY RADIOISOTOPES; BODY; CARBOXYLIC ACIDS; CELL CONSTITUENTS; CHEMICAL REACTIONS; COAGULANTS; DAYS LIVING RADIOISOTOPES; DRUGS; ENZYMES; ESTERASES; FUNCTIONS; HEMATOLOGIC AGENTS; HYDROLASES; HYDROXY ACIDS; ISOTOPE APPLICATIONS; ISOTOPES; LIGHT NUCLEI; MAMMALS; MITOGENS; NUCLEI; ODD-ODD NUCLEI; ORGANIC ACIDS; ORGANIC COMPOUNDS; ORGANS; OXYGEN COMPOUNDS; PHOSPHORUS COMPOUNDS; PHOSPHORUS ISOTOPES; PHOSPHORUS-GROUP TRANSFERASES; PROTEINS; RADIOISOTOPES; RODENTS; TRANSFERASES; VERTEBRATES 550201* -- Biochemistry-- Tracer Techniques