CAST（calpastatin），癌症关联基因，基因ID：831，该基因编码的蛋白质是一种内源性钙蛋白酶（钙依赖半胱氨酸蛋白酶）抑制剂它由一个N-末端结构域L和四个重复的钙蛋白酶抑制结构域（结构域1-4）组成，参与淀粉样前体蛋白的蛋白水解。calpain/calpastatin系统参与许多膜融合事件，如神经囊泡胞吐、血小板和红细胞聚集编码的蛋白质也被认为会影响编码结构蛋白或调节蛋白的基因的表达水平另外，还描述了编码不同亚型的剪接转录变体[由RefSeq提供，2010年6月]The protein encoded by this gene is an endogenous calpain (calcium-dependent cysteine protease) inhibitor. It consists of an N-terminal domain L and four repetitive calpain-inhibition domains (domains 1-4)， and it is involved in the proteolysis of amyloid precursor protein. The calpain/calpastatin system is involved in numerous membrane fusion events， such as neural vesicle exocytosis and platelet and red-cell aggregation. The encoded protein is also thought to affect the expression levels of genes encoding structural or regulatory proteins. Alternatively spliced transcript variants encoding different isoforms have been described. [provided by RefSeq， Jun 2010]。