Signal transduction in smooth muscle - Invited review: Cross-bridge regulation by thin filament-associated proteins

This minireview will cover current concepts on the identity and mechanistic function of smooth muscle actin binding proteins that may regulate actin-m yosin interactions. The potential roles of tropomyosin, caldesmon, calponin , and SM22 will be discussed. The review, for purposes of brevity, will be nonexhaustive but will give an overview of available information on the in vitro biochemistry and potential in vivo function of these proteins. Preter m labor is discussed as a possible example of where thin filament regulatio n may be relevant. Considerable controversy surrounds the putative physiolo gical significance of these proteins, and emphasis will be placed on the ne ed for more experimental work to determine the degree to which tissue- and species-specific effects have clouded the interpretation of functional data .