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sunny静

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[交流] 蛋白质的碳端和氮端

请教各位大侠，蛋白质的碳端和氮端难道是由很多个氨基酸组成的吗？我是一个刚开始接触分子生物学的菜鸟，最近看论文讲修饰c-terminal domain，没太明白是什么意思。

Polytopic membrane proteins are essential for cellular uptake and release of nutrients. To prevent toxic accumulation, rapid shut-off mechanisms are required. Here we show that the soluble cytosolic carboxy terminus of an oligomeric ammonium transporter from Arabidopsis thaliana serves as an allosteric regulator essential for function; mutations in the C-terminal domain, conserved between bacteria, fungi and plants, led to loss of transport activity. When co-expressed with intact transporters, mutants inactivated functional subunits, but left their stability unaffected. Co-expression of two inactive transporters, one with a defective pore, the other with an ablated C terminus, reconstituted activity. The crystal structure of an Archaeoglobus fulgidus ammonium transporter (AMT)1 suggests that the C terminus interacts physically with cytosolic loops of the neighbouring subunit. Phosphorylation of conserved sites in the C terminus2 are proposed as the cognate control mechanism. Conformational coupling between monomers provides a mechanism for tight regulation, for increasing the dynamic range of sensing and memorizing prior events, and may be a general mechanism for transporter regulation.

我想咨询下C-terminal 包含很多氨基酸吗？不是指的蛋白质末端的羧基？膜蛋白的C terminal 是不是可以延伸到cytosol里很长？

Co-expression of two inactive transporters, one with a defective pore, the other with an ablated C terminus, reconstituted activity. 这句话没有明白是什么意思，怎么inactive的两个蛋白一起表达就有了活性了？

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1楼 2014-01-10 12:01:46

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cicelyzh

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sunny静(金币+1): 谢谢参与
wizardfan: 金币+2, 谢谢参与 2014-02-13 09:22:53

你不能断章取义，文章里说的是c-terminal domain，指的是C端结构域。结构域当然有很多氨基酸残基。
文章是说这个transporter的C端结构对功能很重要，如果没有C端结构域，transporter是无功能的。如果共表达失活pore的transporter，可以形成有功能的transporter.