Beall A C, Kato K, Goldenring J R, Rasmussen H, Brophy C M
Department of Surgery, Medical College of Georgia, Augusta, Georgia 30912, USA.
J Biol Chem. 1997 Apr 25;272(17):11283-7. doi: 10.1074/jbc.272.17.11283.
Activation of cyclic nucleotide-dependent signaling pathways leads to the relaxation of various smooth muscles. One of the major phosphorylation events associated with cyclic nucleotide-dependent vasorelaxation in bovine trachealis and carotid artery smooth muscle is the phosphorylation of two 20-kDa phosphoproteins with pI values of 5.7 and 5.9 (previously designated pp8 and pp3, respectively). The present studies sought to determine the identities of pp3 and pp8 in vascular smooth muscle. The phosphopeptide maps for the pp8 and pp3 proteins were similar. Preparative two-dimensional gel electrophoresis and amino acid sequencing of a peptide fragment of the pp3 protein revealed a sequence identical to a 20-kDa heat shock-related protein (HSP20) previously purified from skeletal muscle. Western blot and immunoprecipitation analysis with anti-HSP20 antibodies demonstrated that the pp3 and pp8 proteins are phosphorylated forms of HSP20. In addition, HSP20 could be phosphorylated in vitro by both cAMP-dependent protein kinase and cGMP-dependent protein kinase. These data suggest that the phosphorylation of the heat shock-related protein HSP20 is associated with cyclic nucleotide-dependent relaxation of vascular smooth muscle.
环核苷酸依赖性信号通路的激活会导致各种平滑肌松弛。在牛气管和颈动脉平滑肌中，与环核苷酸依赖性血管舒张相关的主要磷酸化事件之一是两种20 kDa磷蛋白的磷酸化，其等电点分别为5.7和5.9（以前分别称为pp8和pp3）。本研究旨在确定血管平滑肌中pp3和pp8的身份。pp8和pp3蛋白的磷酸肽图谱相似。对pp3蛋白的一个肽片段进行制备性二维凝胶电泳和氨基酸测序，结果显示其序列与先前从骨骼肌中纯化的一种20 kDa热休克相关蛋白（HSP20）相同。用抗HSP20抗体进行的蛋白质印迹和免疫沉淀分析表明，pp3和pp8蛋白是HSP20的磷酸化形式。此外，HSP20在体外可被cAMP依赖性蛋白激酶和cGMP依赖性蛋白激酶磷酸化。这些数据表明，热休克相关蛋白HSP20的磷酸化与血管平滑肌的环核苷酸依赖性舒张有关。
