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部分细胞因子,如表皮生长因子(EGF)、血小板生长因子(PDGF)等信息传递使者到达细胞膜时,其受体是一种酪氨酸激酶.该受体酶有3个结构域(domain),即膜外、跨膜和胞质结构域.细胞因子与膜外结构域结合后,受体激酶本身的酪氨酸残基自动磷酸化,并被激活.受体激酶的激活又能激活细胞质内含SH_2结构域的蛋白质(酶),使其产生第二信使调整细胞的新陈代谢,PLC-γ_1因含有SH_2结构域,因此,它是受体激酶的底物,当被激活时,产生两种第二信使,即二酞基甘油(DAG)和三磷酸肌醇(IP_3).DAG形成后,能激活蛋白激酶C(PKC).PKC是一个酶家族,参与许多细胞活动的调控,特别是细胞分化和增殖的调控.另有人认为PCK还可以活化Na~+-H~+交换机构而导致细胞内pH升高.IP_3形成后则引起Ca~(2+)从钙库中释放(主要来自内质网),Ca~(2+)的释放又可以激活钙调蛋白(CAM)系统,导致底物蛋白质磷酸化,细胞产生相应的生理效应.
Some cytokines such as epidermal growth factor (EGF), platelet growth factor (PDGF) and other information transmission messenger when the cell membrane, its receptor is a tyrosine kinase.This receptor enzyme has three domains, That is, membrane, transmembrane and cytoplasmic domain.Cytokines and extracellular domain binding, the tyrosine residues of the receptor kinase itself is automatically phosphorylated and activated.Receptor kinase activation can activate the cytoplasm SH 2 domain containing protein (enzyme), making it a second messenger to regulate cell metabolism, PLC-γ_1 due to contain SH_2 domain, therefore, it is a receptor kinase substrate, when activated, resulting in two kinds of Two messengers, DAG and IP_3, activate the protein kinase C (PKC) after its formation, and PKC is a family of enzymes involved in the regulation of many cellular activities, particularly in cell differentiation And proliferation.Accordingly, PCK can also activate Na ~ + -H ~ + exchange mechanism to cause intracellular pH increase.IP_3 is formed after the release of Ca ~ (2+) from the calcium store (mainly from the endoplasmic reticulum Network), Ca 2+ release can activate the calmodulin (CAM) system, leading to substrate protein phosphorylation and cell production The corresponding physiological effect.