The interaction of cyclosporin and calmodulin.
The interaction of cyclosporin A and dansyl cyclosporin A with bovine and wheat germ calmodulin has been monitored by measurements of induced changes in dansyl and bound toluidinyl naphthalene sulfonate fluorescence. The interaction is Ca2(+)-dependent and 1:1. Measurements of the efficiency of radiationless energy transfer from bound dansyl cyclosporin A to an acceptor group located on Cys-27 of wheat germ calmodulin suggest that the primary binding site is not located on the N-terminal lobe (residues 1-65). However, studies with proteolytic fragments of calmodulin indicate that elements of the N-terminal half-molecule (residues 1-77) may be involved in the stabilization of the binding site. The binding of cyclosporin alters the physical properties of calmodulin and, in particular, reduces the localized rotational mobility of a fluorescent probe.
Steiner
R F
RF
Department of Chemistry, University of Maryland, Baltimore 21228.
Albaugh
S
S
D000818:Animals; D002147:Calmodulin / Q000378:metabolism*; D002417:Cattle; D055598:Chemical Phenomena; D002627:Chemistry, Physical; D003524:Cyclosporins / Q000378:metabolism*; D008297:Male; D013050:Spectrometry, Fluorescence
D002147:Calmodulin; D003524:Cyclosporins