CONFORMATIONAL CHANGES IN MOLECULAR CONTROL OF MUSCLE CONTRACTION

The McConnell “spin-label” technique (mainly SH-directed labels) has been used to examine whether a structural effect is transmitted across the protein system which controls the contraction of muscle: troponin-tropomyosin-actin. It was found that a spin label attached to tropomyosin responds to Ca2+ fluctuations in the micromolar range only when troponin is present, and that a spin label attached to actin responds only when troponintropomyosin are present. Thus some structural effect appears to be communicated to actin across this control system. © 1969, American Chemical Society. All rights reserved.