Sugai Maki, Saito Masaki, Sukegawa Izumi, Katsushima Yuriko, Kinouchi Yoshitaka, Nakahata Norimichi, Shimosegawa Tooru, Yanagisawa Teruyuki, Sukegawa Jun
Department of Gastroenterology, Tohoku University Graduate School of Medicine, Sendai, Japan.
Biochem Biophys Res Commun. 2003 Nov 7;311(1):24-31. doi: 10.1016/j.bbrc.2003.09.157.
COOH-terminal cytoplasmic domains of G protein-coupled receptors (GPCRs) have been shown to carry determinants that control their cell surface localization, internalization, and recycling. In attempts to seek cellular proteins that mediate these processes of PTH/PTH-related protein receptor (PTHR), one of the class B GPCRs, we have found that Tctex-1, a 14kDa light chain of cytoplasmic dynein motor complex, interacts with the COOH-terminal tail of the receptor. A 34-amino-acid stretch of the receptor responsible for binding to Tctex-1 has a bipartite structure consisting of a motif previously implicated in binding of some proteins to Tctex-1 and a putative new consensus sequence. Site-directed mutations or a 20-amino-acid deletion in the bipartite consensus binding sequence abolished the association of the PTHR COOH terminus with Tctex-1 in vitro. A GFP-fused mutant PTHR impaired in binding to Tctex-1 expressed in MDCK cells showed a decreased rate of internalization in response to PTH compared to that of the wild type.
G蛋白偶联受体（GPCRs）的羧基末端胞质结构域已被证明携带控制其细胞表面定位、内化和再循环的决定因素。为了寻找介导B类GPCR之一甲状旁腺激素/甲状旁腺激素相关蛋白受体（PTHR）这些过程的细胞蛋白，我们发现细胞质动力蛋白复合物的14kDa轻链Tctex-1与该受体的羧基末端尾巴相互作用。受体中负责与Tctex-1结合的一段34个氨基酸的序列具有二分结构，由一个先前与某些蛋白质与Tctex-1结合有关的基序和一个推定的新共有序列组成。二分共有结合序列中的定点突变或20个氨基酸的缺失消除了PTHR羧基末端在体外与Tctex-1的结合。与野生型相比，在MDCK细胞中表达的与Tctex-1结合受损的GFP融合突变型PTHR对PTH的内化速率降低。
