Open AccessProtein tyrosine phosphorylation in the cell cycle of BALB/c 3T3 fibroblasts.
Author(s) -
Alex O. Morla,
Jean Y. J. Wang
Publication year - 1986
Publication title -
proceedings of the national academy of sciences of the united states of america
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.011
H-Index - 771
eISSN - 1091-6490
pISSN - 0027-8424
DOI - 10.1073/pnas.83.21.8191
Subject(s) - tyrosine phosphorylation , phosphorylation , tyrosine , protein tyrosine phosphatase , protein phosphorylation , biology , cycloheximide , microbiology and biotechnology , cell cycle , receptor tyrosine kinase , cell , biochemistry , protein biosynthesis , protein kinase a
Cell cycle-dependent regulation of protein tyrosine phosphorylation in normal BALB/c 3T3 fibroblasts was examined by immunoblotting with a high-affinity antibody specific for phosphotyrosine. At least 15 different tyrosine-phosphorylated proteins are found in normal 3T3 cells. The level of tyrosine phosphorylation is higher in growing cells than in quiescent cells. However, a prominent tyrosine-phosphorylated protein of Mr 150,000 is present in quiescent cells, and its level is inversely proportional to the growth rate of these fibroblasts. Stimulation of quiescent cells with serum causes a major, yet transient, increase in tyrosine phosphorylation. The immediate tyrosine phosphorylation reactions in response to serum stimulation are independent of protein synthesis, but tyrosine phosphorylation reactions occurring later in the G1 phase of the cell cycle are inhibited by cycloheximide. Thus, tyrosine phosphorylation of proteins in normal 3T3 cells occurs predominantly at the G0 to G1 transition of the cell cycle. Maintenance of steady-state tyrosine phosphorylation is dependent on the presence of serum, but at least one tyrosine phosphorylation reaction occurs in the absence of cell growth.