Immunocytochemical localization of glyceraldehyde-3-phosphate dehydrogenase in cultured endothelial and smooth muscle cells.

Abstract

The presence and distribution of glyceraldehyde-3-phosphate dehydrogenase (GPDH) in cultured bovine aortic endothelial cell (EC) and smooth muscle cell (SMC) were studied. For this purpose, we purified GPDH from human and bovine red blood cell (RBC) membranes and used it as antigen; anti-GPDH serum and affinity purified IgG were prepared. GPDH has been identified in the whole extracts of EC and SMC as a polypeptide having the same electrophoretic mobility as RBC protein. In addition, GPDH digested with V8 protease and analyzed by one dimensional peptide mapping presented the same pattern for the three cell types examined. Anti-RBC-GPDH cross-reacted with the polypeptide from EC and SMC. The intracellular localization of GPDH in EC and SMC was investigated by indirect immunofluorescence microscopy using affinity purified anti-GPDH. We found that the antigen exhibits a diffuse cytoplasmic distribution in both cell types; in addition, EC contained the antigen in the nucleus. The nuclear GPDH-like protein in EC has a characteristic pattern, suggesting yet unknown implications of GPDH in the cell metabolism.