IDENTIFICATION AND POSSIBLE LOCALIZATION OF CGMP-DEPENDENT PROTEIN-KINASE IN BOVINE AORTIC ENDOTHELIAL-CELLS

Endothelial-derived nitric oxide (NO) is an important intercellular me ssenger. Although endothelial cells contain both nitric oxide synthase and soluble guanylate cyclase, the nature of receptor proteins for cG MP is uncertain. Based on previous work in vascular smooth muscle cell s which indicates that the cGMP-dependent protein kinase (cGK) is part ially associated with the cytoskeleton, we determined that cGK was pre sent in non-cytosolic fractions of endothelial cells. The data reveal that cGK is found only in Triton-soluble extracts of particulate fract ions from bovine aortic endothelial cells and provide the first eviden ce for the existence of cGK in this cell type based on immunoreactivit y, immunofluorescence microscopy and phosphotransferase activity. The limited distribution of endothelial cell cGK may explain why this kina se has not been heretofore identified in endothelial cells. (C) 1994 A cademic Press, Inc.