Drosophila TRP channels require a protein with a distinctive motif encoded by the inaF locus
Drosophila TRP channels require a protein with a distinctive motif encoded by the inaF locus
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DOI：
10.1073/pnas.0708368104
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发表时间：
2007-11-06
影响因子：
11.1
通讯作者：
Nash, Howard A.
中科院分区：
文献类型：
--
作者：
Cheng, Yuzhong;Nash, Howard A.
在脊椎动物和无脊椎动物中，Trp超家族的离子通道都受到各种辅助因素的影响，但相互作用的蛋白质列表是不完整的。虽然以前的工作表明，果蝇的色氨酸功能受到INAF基因突变的干扰，但这种影响的机制仍然不清楚。在这里，我们展示了一个以前被忽视的小蛋白，INAF-B，是由该基因编码的，并在视网膜生理学中发挥其关键作用。81-aa的INAF-B基因产物是一种完整的膜蛋白，它与TRIP通道共同定位于rhab结构域。免疫沉淀实验表明，这两种蛋白质参与了一个复合体，印迹实验表明，在没有对方的情况下，两种蛋白质中的一种都不能存活。这两种蛋白质通常都是一个大型超分子组装的一部分，即信号丛，但即使在没有这种结构的支架的情况下，它们的相互作用也会持续下去。INAF基因座编码另外三种蛋白质，除了一个包含跨膜结构域的32-AA残基外，每种蛋白质都与INAF-B有所不同。这个保守的序列定义了一个INAF基序，它的代表存在于各种生物的蛋白质中，如线虫、鱼和人类。考虑到INAF-B的作用，这些蛋白质是TRIP超家族其他成员相互作用的很好的候选蛋白。
In both vertebrates and invertebrates, ion channels of the TRP superfamily are known to be influenced by a variety of accessory factors, but the list of interacting proteins is acknowledged to be incomplete. Although previous work showed that Drosophila TRP function is disrupted by mutations in the inaF locus, the mechanism of this effect has remained obscure. Here we show that a previously overlooked small protein, INAF-B, is encoded by the locus and fulfills its critical role in retinal physiology. The 81-aa INAF-B gene product is an integral membrane protein that colocalizes to rhab-domeres along with TRIP channels. Immumoprecipitation experiments demonstrate that the two proteins participate in a complex, and blotting experiments show that neither protein survives in the absence of the other. Both proteins are normally part of a large supramolecular assembly, the signalplex, but their interaction persists even in the absence of the scaffold for this structure. The inaF locus encodes three other proteins, each of which has diverged from INAF-B except for a 32-aa block of residues that encompasses a transmembrane domain. This conserved sequence defines an inaF motif, representatives of which are found in proteins from organisms as diverse as nematodes, fish, and humans. Given the role of INAF-B, these proteins are good candidates for interacting partners of other members of the TRIP superfamily.