Kerrick W G, Bolles L L
J Cell Physiol. 1982 Sep;112(3):307-15. doi: 10.1002/jcp.1041120302.
The Ca2+ activation mechanism of the longitudinal body wall muscles of Parastichopus californicus (sea cucumber) was studied using skinned muscle fiber bundles. Reversible phosphorylation of the myosin light chains correlated with Ca2+-activated tension and relaxation. Pretreatment of the skinned fibers with AT-P gamma S and high Ca2+ (10(-5)M) resulted in irreversible thiophosphorylation of the myosin light chains and activation of a Ca2+ insensitive tension. In contrast, pretreatment with low Ca2+ (10(-8)M) and ATP gamma S results in no thiophosphorylation of the myosin light chains or irreversible activation of tension. These results are consistent with a Ca2+-sensitive myosin light chain kinase/phosphatase system being responsible for the activation of the muscle. Other agents known to have an effect upon the Ca2+-activated tension in skinned vertebrate smooth muscle fibers (trifluoperazine, catalytic subunit of the cyclic AMP-dependent protein kinase, and calmodulin) did not have an effect on myosin light chain phosphorylation or Ca2+-activated tension. These results suggest a different type of myosin light chain kinase than is found in vertebrate smooth muscle is responsible for the activation of parastichopus longitudinal body wall muscle.
利用去膜肌纤维束研究了加州拟刺参（海参）纵体壁肌肉的Ca2+激活机制。肌球蛋白轻链的可逆磷酸化与Ca2+激活的张力和松弛相关。用ATPγS和高Ca2+（10(-5)M）预处理去膜纤维导致肌球蛋白轻链的不可逆硫代磷酸化和Ca2+不敏感张力的激活。相反，用低Ca2+（10(-8)M）和ATPγS预处理不会导致肌球蛋白轻链的硫代磷酸化或张力的不可逆激活。这些结果与Ca2+敏感的肌球蛋白轻链激酶/磷酸酶系统负责肌肉激活一致。已知对去膜脊椎动物平滑肌纤维中Ca2+激活的张力有影响的其他试剂（三氟拉嗪、环磷酸腺苷依赖性蛋白激酶的催化亚基和钙调蛋白）对肌球蛋白轻链磷酸化或Ca2+激活的张力没有影响。这些结果表明，与脊椎动物平滑肌中发现的不同类型的肌球蛋白轻链激酶负责拟刺参纵体壁肌肉的激活。
