Hori M, Saito S, Shin Y Z, Ozaki H, Fusetani N, Karaki H
Department of Veterinary Pharmacology, Faculty of Agriculture, University of Tokyo, Japan.
FEBS Lett. 1993 May 10;322(2):151-4. doi: 10.1016/0014-5793(93)81557-g.
A toxin isolated from marine sponge, mycalolide-B, inhibited smooth muscle contractions without changing cytosolic Ca2+ levels. It also inhibited Ca(2+)-induced contraction in permeabilized smooth muscles. In native actomyosin prepared from chicken gizzard, mycalolide-B inhibited superprecipitation and Mg(2+)-ATPase activity stimulated by Ca2+ without changing myosin light chain phosphorylation. In the permeabilized muscle and native actomyosin preparation thiophosphorylated with ATP gamma S, mycalolide-B inhibited ATP-induced contraction and Mg(2+)-ATPase activity, respectively, in the absence of Ca2+. Mycalolide-B also inhibited Mg(2+)-ATPase activity of skeletal muscle native actomyosin. Mycalolide-B had no effect on calmodulin-stimulated (Ca(2+)-Mg2+)-ATPase activity of erythrocyte membranes. These results suggest that mycalolide-B selectively inhibits actin-myosin interaction.
从海洋海绵中分离出的毒素麦考内酯 - B可抑制平滑肌收缩，而不改变胞质Ca2+水平。它还能抑制通透化平滑肌中Ca(2+)诱导的收缩。在从鸡胗制备的天然肌动球蛋白中，麦考内酯 - B抑制了由Ca2+刺激的超沉淀和Mg(2+)-ATP酶活性，而不改变肌球蛋白轻链磷酸化。在通透化肌肉和用ATPγS硫代磷酸化的天然肌动球蛋白制剂中，麦考内酯 - B分别在无Ca2+的情况下抑制了ATP诱导的收缩和Mg(2+)-ATP酶活性。麦考内酯 - B还抑制骨骼肌天然肌动球蛋白的Mg(2+)-ATP酶活性。麦考内酯 - B对红细胞膜的钙调蛋白刺激的(Ca(2+)-Mg2+)-ATP酶活性没有影响。这些结果表明，麦考内酯 - B选择性地抑制肌动蛋白 - 肌球蛋白相互作用。
