Haller H, Smallwood J I, Rasmussen H
Department of Internal Medicine, Yale University School of Medicine, New Haven, CT 06510.
Biochem J. 1990 Sep 1;270(2):375-81. doi: 10.1042/bj2700375.
Using intact muscle strips from the bovine carotid artery, the time course of translocation of protein kinase C (PKC) from the cytosol to the membrane fraction was measured in response to various agonists that induce contractile responses. PKC activity was assessed by Ca2+/phospholipid-dependent phosphorylation of histone. Exposure of the muscle strips to phorbol ester (12-deoxyphorbol 13-isobutyrate) induced a rapid and sustained translocation of PKC from the cytosol to the membrane fraction, and a slowly developing but sustained contractile response. Histamine induced a comparable initial translocation of PKC to the membrane which then decreased somewhat to a stable plateau significantly above basal values. Histamine also led to a rapid and sustained increase in tension. Angiotensin I, which caused a rapid but transient contraction, induced a rapid initial translocation of PKC to the membrane. The membrane-associated PKC then declined to a stable plateau significantly lower than that seen after a histamine-induced response, and only slightly above the basal value. Endothelin, which induced a sustained contraction, caused a sustained translocation of PKC from the cytosol to the membrane. In contrast, although exposure to 35 mM-KCl induced a rapid and sustained contraction, it caused only a transient translocation of PKC; the membrane-associated PKC returned to its basal value within 20 min. These results demonstrate that PKC in intact smooth muscle can be rapidly translocated to the membrane and remains membrane-bound during sustained phorbol ester- or agonist-induced contractions, but that such a sustained translocation of PKC does not occur during prolonged stimulation with KCl.
利用来自牛颈动脉的完整肌条，测定了蛋白激酶C（PKC）从胞质溶胶向膜组分转位的时间进程，以响应各种诱导收缩反应的激动剂。通过组蛋白的Ca2 + /磷脂依赖性磷酸化来评估PKC活性。将肌条暴露于佛波酯（12 - 脱氧佛波醇13 - 异丁酸酯）会诱导PKC从胞质溶胶快速且持续地转位至膜组分，并引发缓慢发展但持续的收缩反应。组胺诱导PKC向膜发生类似的初始转位，随后有所下降至显著高于基础值的稳定平台期。组胺还导致张力迅速且持续增加。血管紧张素I引起快速但短暂的收缩，诱导PKC快速初始转位至膜。随后膜相关的PKC下降至显著低于组胺诱导反应后所见水平的稳定平台期，仅略高于基础值。内皮素诱导持续收缩，导致PKC从胞质溶胶持续转位至膜。相比之下，尽管暴露于35 mM - KCl会诱导快速且持续的收缩，但它仅引起PKC的短暂转位；膜相关的PKC在20分钟内恢复至基础值。这些结果表明，完整平滑肌中的PKC可快速转位至膜，并在持续的佛波酯或激动剂诱导的收缩过程中保持与膜结合，但在用KCl进行长时间刺激时不会发生PKC的这种持续转位。
