Involvement of calponin and caldesmon in sustained contraction of arterial smooth muscle.
The molecular mechanism of smooth muscle contraction was approached by a novel method, covalent 14C-labeling. Intra- and intermolecular protein interactions during contractile activity are reflected by changed reactivity of protein side chains; these can be detected by reagents which readily permeate through the muscle membrane without affecting the contractility and form covalent bonds with proteins in the muscle. The incorporation of 14CH2ICONH2 into proteins of 1-hour histamine contracted versus resting porcine carotid arterial muscles was determined. Out of fourteen 14C-labeled proteins analyzed, only two showed a change in reactivity during sustained contraction. The incorporation of 14CH2ICONH2 into calponin and caldesmon in contracted muscles was about 66% of that into these same proteins in resting muscles. A transformation of calponin and caldesmon molecules from an extended to a more compact conformation explains the decreased reactivity.
Bárány
K
K
Department of Physiology and Biophysics, College of Medicine, University of Illinois, Chicago 60612.
Polyák
E
E
Bárány
M
M
D000818:Animals; D002135:Calcium-Binding Proteins / Q000737:chemistry / Q000502:physiology*; D002148:Calmodulin-Binding Proteins / Q000737:chemistry / Q000502:physiology*; D002250:Carbon Radioisotopes; D002339:Carotid Arteries; D004229:Dithiothreitol / Q000494:pharmacology; D006632:Histamine / Q000494:pharmacology; D007460:Iodoacetamide / Q000378:metabolism; D008840:Microfilament Proteins; D009119:Muscle Contraction / Q000187:drug effects / Q000502:physiology*; D009124:Muscle Proteins / Q000378:metabolism; D009131:Muscle, Smooth, Vascular / Q000502:physiology*; D011489:Protein Denaturation; D013438:Sulfhydryl Compounds / Q000378:metabolism; D013552:Swine; D000096985:Calponins
D002135:Calcium-Binding Proteins; D002148:Calmodulin-Binding Proteins; D002250:Carbon Radioisotopes; D004229:Dithiothreitol; D006632:Histamine; D007460:Iodoacetamide; D008840:Microfilament Proteins; D009124:Muscle Proteins; D013438:Sulfhydryl Compounds; D000096985:Calponins