NAC(初期多肽相关复合体)及其α亚基NACA

NAC(Nascent Polypeptide-associated Complex) and Its Alpha Subunit NACA

初期多肽相关复合体(nascent polypeptide-associated complex,NAC)是新生肽链从核糖体上延伸出来第一个接触的异二聚体蛋白复合体,从古生菌、酵母到哺乳动物都高度保守。NAC是一个具有多种功能的蛋白,包括保护新生肽链、调控新生肽转位进入内质网和线粒体、肌肉损伤修复等。其α亚基NACA/αNAC(nascent polypeptide-associated complex alpha subunit)主要在转录调控中起作用。此外,NACA还能调控FADD(Fas-associated with death domain protein)所介导的信号转导。在一些病毒性疾病,如乙肝、丙肝和非洲猪瘟中,NACA能与病毒的某些蛋白相互作用,致使机体功能紊乱。在老年痴呆症和唐氏综合征患者脑细胞中,与正常水平相比,NACA表达下调。

NAC（nascent polypeptide-associated complex） is the first cytosolic heterodimeric protein complex to contact nascent polypeptide chains emerging from ribosomes and is evolutionarily conserved in the genomes from archaea, yeast to mammals. NAC is found to be a multifunctional protein which can shield nascent chains, regulate nascent chains translocating into endoplasmic reticulum and mitochondria, repair muscle damage and so on. However, its α subunit NACA/αNAC（nascent polypeptide-associated complex alpha subunit） is identified mainly functioning in transcriptional regulation. It may play a role in FADD-mediated signal transduction process. Moreover, in many viral diseases, such as the Viral Hepatitis Type B, C and the African swine fever, it is found to be able to interact with the relevant viral protein to cause physiological disorders. Even in the brain tissues of patients with Alzheimer＇s disease and Down syndrome, NACA is found downregulated.