Substrates of cGMP kinase in vascular smooth muscle and their role in the relaxation process.
G1 is a hitherto unidentified substrate (molecular mass about 120 kDa) of the cGMP-dependent kinase, although its presence in vascular smooth muscle sarcolemma has been known for many years. Since it represents the major target of the G-kinase in smooth muscle, its physicochemical and biochemical properties were investigated. Solubilization of G1 required a detergent: with Triton X-100, however, its extraction only occurred in the presence of high salt concentrations or millimolar ATP. These properties are typical for a membrane protein interacting with a nonmembraneous sedimentable moiety. Cupric phenanthroline-catalyzed oxidation revealed that the G1 phosphoprotein could be oxidatively cross-linked to a sedimentable moiety. The latter was identified by two-dimensional (nonreduced/reduced) gel electrophoresis as actin which is attached to the sarcolemma. Furthermore, DNase I affinity chromatography demonstrated an interaction of solubilized G1 with actin. The results suggest a role of G1 in the plasma membrane-cytoskeleton interaction in smooth muscle cells.
Baltensperger
K
K
Department of Biochemistry, Swiss Federal Institute of Technology (ETH), Zürich.
Chiesi
M
M
Carafoli
E
E
D000199:Actins / Q000378:metabolism; D000818:Animals; D001011:Aorta / Q000502:physiology*; D002846:Chromatography, Affinity; D003432:Cross-Linking Reagents; D003850:Deoxyribonuclease I; D015180:Electrophoresis, Gel, Two-Dimensional; D004591:Electrophoresis, Polyacrylamide Gel; D008565:Membrane Proteins / Q000302:isolation & purification / Q000378:metabolism*; D009126:Muscle Relaxation; D009131:Muscle, Smooth, Vascular / Q000502:physiology*; D009219:Myosin-Light-Chain Kinase / Q000378:metabolism; D010750:Phosphoproteins / Q000302:isolation & purification; D011494:Protein Kinases / Q000378:metabolism*; D012508:Sarcolemma / Q000502:physiology*; D013552:Swine
D000199:Actins; D003432:Cross-Linking Reagents; D008565:Membrane Proteins; D010750:Phosphoproteins; D011494:Protein Kinases; D009219:Myosin-Light-Chain Kinase; D003850:Deoxyribonuclease I