Properties of desensitized myosin B of chicken gizzard.

In order to explore the regulatory mechanism of smooth muscle contraction, properties of desensitized myosin B (natural actomyosin) prepared from chicken gizzard was investigated. Myosin B desensitized by the method of Ebashi (1988) was resensitized by the addition of the smooth muscle extract. Troponin of rabbit skeletal muscle did not resensitize the desensitized myosin B, but it increased the extent of resensitization when the desensitized myosin B was resensitized incompletely by the addition of small amount of the extract. Among three components (C, I, T) of troponin, this action in promoting the resensitization of desensitized myosin B was found only in troponin T. This finding suggests that troponin T-like factor is present in smooth muscle myosin B.