现有资料显示II型cGMP依赖性蛋白激酶（PKG II）不含信号肽，是分布于细胞内的蛋白激酶。本项目前期研究发现，PKG II定位于细胞的内质网和高尔基体，存在于人及小鼠血清中，能使EGFR胞外段磷酸化，阻断EGF对EGFR的激活，提示PKG II可能是一个分泌性蛋白激酶。在此基础上，本项目将研究PKG II分泌的分子机制，特别是其氮端豆蔻酰修饰和氨基酸序列在引导PKG II肽链进入“内质网-高尔基体”分泌途径中的作用；以与EGFR同属受体酪氨酸激酶（RTK）家族的VEGFR、PDGFR和c-Met为对象， 研究PKG II 是否通过使这些RTKs胞外段发生磷酸化而抑制它们的激活，进一步探讨PKG II的胞外靶点。研究将阐明一条新的蛋白质分泌途径，并有助于开辟蛋白激酶研究的新领域。

The existing research data show that Type II cGMP dependent protein kinase (PKG II) has no signal peptide and is an intracellular-located serine/threonine protein kinase. The previous study of this project found that PKG II was located on endoplasmic reticulum(ER) and Golgi apparatus, and existed in serum of human and mouse. It could cause phosphorylation of the extracellular domain of epidermal growth factor receptor (EGFR) and block the EGF-initiated activation of EGFR. This indicated that PKG II could be a secreted protein kinase. On this basis, this project will study molecular mechanism of PKG II secretion, especially the role of myristoylation modulation and amino acid sequence of N-terminal of PKG II in guiding PKG II peptide chain to enter “ER-Golgi apparatus” secretion pathway. In the meantime, the project will take VEGFR, PDGFR and c-Met, the members of receptor tyrosine kinases (RTKs) family, as objects to investigate whether PKG II can phosphorylate the extracellular domains of these RTKs and block their activation, exploring the extracellular targets of secreted PKG II. The research of this project will elucidate a new protein secretion pathway and can help to open up a new research field of protein kinases.