Movsesian M A, Morris G L, Wang J H, Krall J
Department of Internal Medicine (Cardiology), Salt Lake City Veterans Affairs Medical Center, Utah.
Second Messengers Phosphoproteins. 1992;14(3):151-61.
The correlation between phospholamban and sarcoplasmic reticulum Ca(2+)-transporting ATPase levels and the magnitude of phospholamban-mediated stimulation of sarcoplasmic reticulum Ca2+ transport was examined in microsomes prepared from rabbit and canine cardiac, slow twitch and fast twitch skeletal muscle. Phospholamban was absent from microsomes prepared from fast twitch skeletal muscle but present at comparable levels in microsomes prepared from cardiac and slow twitch skeletal muscle. Levels of Ca(2+)-transporting ATPase were higher in microsomes prepared from slow twitch skeletal muscle than in microsomes prepared from cardiac muscle, however, and ratios of phospholamban to Ca(2+)-transporting ATPase were several fold greater in microsomes prepared from cardiac muscle than in microsomes prepared from slow twitch skeletal muscle. Stimulation of ATP-dependent Ca2+ transport following phosphorylation of phospholamban by cAMP-dependent protein kinase or incubation with anti-phospholamban monoclonal antibody was observed only in cardiac muscle microsomes. These observations indicate that phospholamban, while present in both cardiac and slow twitch skeletal muscle, may be involved in the hormonal regulation of sarcoplasmic reticulum Ca2+ transport only in the former, and that the lack of phospholamban-mediated stimulation of Ca2+ transport in slow twitch skeletal muscle sarcoplasmic reticulum may result from the lower ratio of phospholamban to Ca(2+)-transporting ATPase in this tissue.
在从兔和犬的心脏、慢肌和快肌骨骼肌制备的微粒体中，研究了受磷蛋白与肌浆网Ca(2+)转运ATP酶水平之间的相关性，以及磷蛋白介导的肌浆网Ca2+转运刺激的程度。快肌骨骼肌制备的微粒体中不存在受磷蛋白，但在心脏和慢肌骨骼肌制备的微粒体中，其水平相当。然而，慢肌骨骼肌制备的微粒体中Ca(2+)转运ATP酶的水平高于心肌制备的微粒体，并且心肌制备的微粒体中受磷蛋白与Ca(2+)转运ATP酶的比率比慢肌骨骼肌制备的微粒体高几倍。仅在心肌微粒体中观察到环磷酸腺苷依赖性蛋白激酶使受磷蛋白磷酸化或与抗受磷蛋白单克隆抗体孵育后对ATP依赖性Ca2+转运的刺激。这些观察结果表明，受磷蛋白虽然存在于心脏和慢肌骨骼肌中，但可能仅在前者中参与肌浆网Ca2+转运的激素调节，并且慢肌骨骼肌肌浆网中缺乏受磷蛋白介导的Ca2+转运刺激可能是由于该组织中受磷蛋白与Ca(2+)转运ATP酶的比率较低。
