N-ethylmaleimide inhibits polymerization of myorod, a contractile protein of thick filaments of molluscan smooth muscles

The effect of N-ethylmaleimide on the polymerization of myorod, a protein of molluscan smooth muscles, which is colocalized with myosin on the surface of paramyosin core of thick filaments and is a product of the alternative splicing of the gene of heavy myosin chains, was studied. It was shown that myorod modified by N-ethylmaleimide completely loses the polymerization ability but acquires the ability to aggregate in the presence of Mg2+. At the same time, treatment of molluscan myosin with N-ethylmaleimide did not affect its polymerization. It was supposed that the effect of N-ethylmaleimide on myorod polymerization is related to the modification of the myorod SH domain containing Cys722.