Institute for Biophysics, University of Linz, A-4020 Linz, Austria.
Institute for Biophysics, University of Linz, A-4020 Linz, Austria.
J Biol Chem. 2012 Oct 12;287(42):35612-35620. doi: 10.1074/jbc.M112.400952. Epub 2012 Aug 29.
TRP proteins mostly assemble to homomeric channels but can also heteromerize, preferentially within their subfamilies. The TRPC1 protein is the most versatile member and forms various TRPC channel combinations but also unique channels with the distantly related TRPP2 and TRPV4. We show here a novel cross-family interaction between TRPC1 and TRPV6, a Ca(2+) selective member of the vanilloid TRP subfamily. TRPV6 exhibited substantial co-localization and in vivo interaction with TRPC1 in HEK293 cells, however, no interaction was observed with TRPC3, TRPC4, or TRPC5. Ca(2+) and Na(+) currents of TRPV6-overexpressing HEK293 cells are significantly reduced by co-expression of TRPC1, correlating with a dramatically suppressed plasma membrane targeting of TRPV6. In line with their intracellular retention, remaining currents of TRPC1 and TRPV6 co-expression resemble in current-voltage relationship that of TRPV6. Studying the N-terminal ankyrin like repeat domain, structurally similar in the two proteins, we have found that these cytosolic segments were sufficient to mediate a direct heteromeric interaction. Moreover, the inhibitory role of TRPC1 on TRPV6 influx was also maintained by expression of only its N-terminal ankyrin-like repeat domain. Our experiments provide evidence for a functional interaction of TRPC1 with TRPV6 that negatively regulates Ca(2+) influx in HEK293 cells.
TRP 蛋白主要组装成同源通道，但也可以异源二聚体化，优先在其亚家族内。TRPC1 蛋白是最通用的成员，形成各种 TRPC 通道组合，但也与远亲的 TRPP2 和 TRPV4 形成独特的通道。我们在这里展示了 TRPV6（香草素 TRP 亚家族的一种 Ca2+选择性成员）与 TRPC1 之间的新型跨家族相互作用。在 HEK293 细胞中，TRPV6 与 TRPC1 表现出大量的共定位和体内相互作用，但是与 TRPC3、TRPC4 或 TRPC5 没有观察到相互作用。TRPC1 的共表达显著降低了 TRPV6 过表达的 HEK293 细胞中的 Ca2+和 Na+电流，这与 TRPV6 的质膜靶向作用明显受到抑制有关。与它们的细胞内保留一致，TRPC1 和 TRPV6 共表达的剩余电流在电流-电压关系上类似于 TRPV6。研究两种蛋白质结构相似的 N 端锚蛋白样重复结构域，我们发现这些细胞内段足以介导直接的异源二聚体相互作用。此外，TRPC1 对 TRPV6 内流的抑制作用也通过仅表达其 N 端锚蛋白样重复结构域得以维持。我们的实验提供了 TRPC1 与 TRPV6 之间功能相互作用的证据，该相互作用负调节 HEK293 细胞中的 Ca2+内流。
