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什么是Caspase级联反应

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什么是Caspase级联反应
生化当中经常提到CASPASE级联反应,究竟什么是CASPASE级联反应,它有多少条通路,每条通路之间的关系是什么
什么是Caspase级联反应
Caspase 是一类与凋亡密切相关的蛋白水解酶家族,以Caspase前体酶原的形式存在大多后生动物的细胞中.
Caspase在凋亡信号的作用下首先激活启动型Caspase引发Caspase级联反应(Caspase Cascade),然后通过活化的执行型Caspase裂解特异性底物导致细胞凋亡.Caspase的活化是导致细胞凋亡的中心环节,位于Caspase级联反应上游的启动型Caspase的和下游的执行型Caspase有着明显不同的活化机制.
有一个英文的简单的描述:
Caspase Cascade
Apoptosis or programmed cell death is triggered by a variety of stimuli,including cell surface receptors like FAS,the mitochondrial response to stress,and factors released from cytotoxic T cells.The caspases comprise a class of cysteine proteases many members of which are involved in apoptosis.The caspases convey the apoptotic signal in a proteolytic cascade,with caspases cleaving and activating other caspases that subsequently degrade cellular targets that lead to cell death.The activating caspases include caspase-8 and caspase-9.Caspase-8 is the initial caspase activated in response to receptors with a death domain that interacts with FADD.The mitochondrial stress pathway begins with the release of cytochrome c from mitochondria,which then interacts with Apaf-1,causing self-cleavage and activation of caspase-9.The effector caspases,caspase-3,-6 and-7 are downstream of the activator caspases and act to cleave various cellular targets.Granzyme B and perforin,proteins released by cytotoxic T cells,induce apoptosis in target cells by forming transmembrane pores and triggering apoptosis,perhaps through cleavage of caspases.Caspase independent mechanisms of granzyme B-mediated apoptosis have been suggested.