
Overview:
PAK proteins is a family of serine/threonine kinases that serve as targets for the small GTP binding proteins, CDC42 and RAC1, and have been implicated in a wide range of biological activities. The p21 activated kinases (PAK) are critical effectors that link Rho GTPases to cytoskeleton reorganization and nuclear signaling. PAK2 is activated by proteolytic cleavage during caspase-mediated apoptosis, and may play a role in regulating the apoptotic events in the dying cell (1). The CDC42 and RAC1 induce autophosphorylation of PAK2, which stimulates sustained phosphorylation of other substrates (2).
References:
1. Koeppel, M. A. et.al: Identification and characterization of PS-GAP as a novel regulator of caspase-activated PAK-2. J. Biol. Chem. 279: 53653-53664, 2004.2. Martin, G. A. et.al: A novel serine kinase activated by rac1/CDC42Hs-dependent autophosphorylation is related to PAK65 and STE20. EMBO J. 14: 1970-1978, 1995.
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二、补体(complement,C)是存在于正常人和动物血清与组织液中的一组经活化后具有酶活性的蛋白质。早在19世纪末Bordet即证实,新鲜血液中含有一种不耐热的成分,可辅助和补充特异性抗体,介导免疫溶菌、溶血作用,故称为补体。补体是由30余种可溶性蛋白、膜结合性蛋白和补体受体组成的多分子系统,故称为补体系统(complementsystem)。根据补体系统各成分的生物学功能,可将其分为补体固有成分、补体调控成分和补体受体(CR)。

