Characterization of p51/52, a cell-growth regulated protein of WI-38 cells.
A number of proteins have been identified whose expression or activity is regulated by cell growth. We have produced a monoclonal antibody against a new cell-growth regulated protein found in normal human fibroblasts. We have shown that this antibody recognizes a 51/52-kDa doublet (p51/52) found mainly in normal cells. This doublet is sensitive to degradation by the calcium-activated protease, calpain, breaking down to a 37/38-kDa doublet. The relative amount of the two members of the 51/52-kDa doublet changes when serum-starved cells reenter the cell cycle. Quiescent cells express mainly the 51-kDa form; the 52-kDa form becomes more abundant upon refeeding serum-starved cells. Transformed cells express either very small amounts of this doublet, and then predominantly the 52-kDa form, or no detectable amount of either form. These characteristics distinguish this molecule from several other known growth-regulated proteins such as statin and the anti-oncogene p53.
Rampalli
A
A
Department of Biology, University of Toledo, Ohio 43606.
Smith
C J
CJ
Wheelock
M J
MJ
D000911:Antibodies, Monoclonal / Q000032:analysis / Q000276:immunology; D002118:Calcium / Q000502:physiology; D002154:Calpain / Q000494:pharmacology; D002462:Cell Membrane / Q000737:chemistry / Q000648:ultrastructure; D002478:Cells, Cultured; D015180:Electrophoresis, Gel, Two-Dimensional; D000939:Epitopes / Q000276:immunology; D005347:Fibroblasts / Q000737:chemistry* / Q000648:ultrastructure; D005455:Fluorescent Antibody Technique; D006133:Growth Substances / Q000032:analysis* / Q000276:immunology; D006801:Humans; D015151:Immunoblotting; D011506:Proteins / Q000032:analysis* / Q000276:immunology
D000911:Antibodies, Monoclonal; D000939:Epitopes; D006133:Growth Substances; D011506:Proteins; D002154:Calpain; D002118:Calcium