Medical Research Council Anatomical Neuropharmacology Unit, Oxford, UK.
FEBS J. 2010 Dec;277(24):5174-89. doi: 10.1111/j.1742-4658.2010.07935.x. Epub 2010 Nov 19.
The copines are a family of C2- and von Willebrand factor A-domain-containing proteins that have been proposed to respond to increases in intracellular calcium by translocating to the plasma membrane. The copines have been reported to interact with a range of cell signalling and cytoskeletal proteins, which may therefore be targeted to the membrane following increases in cellular calcium. However, neither the function of the copines, nor their actual movement to the plasma membrane, has been fully established in mammalian cells. Here, we show that copines-1, -2, -3, -6 and -7 respond differently to a methacholine-evoked intracellular increase in calcium in human embryonic kidney cell line-293 cells, and that their membrane association requires different levels of intracellular calcium. We demonstrate that two of these copines associate with different intracellular vesicles following calcium entry into cells, and identify a novel conserved amino acid sequence that is required for their membrane translocation in living cells. Our data show that the von Willebrand factor A-domain of the copines modulates their calcium sensitivity and intracellular targeting. Together, these findings suggest a different set of roles for the members of this protein family in mediating calcium-dependent processes in mammalian cells.
Copines 是一类含有 C2 和 von Willebrand 因子 A 结构域的蛋白，据推测，它们可以通过向质膜转位来响应细胞内钙离子的增加。已有报道称，Copines 与一系列细胞信号和细胞骨架蛋白相互作用，因此，在细胞内钙离子增加后，这些蛋白可能会被靶向到质膜。然而，Copines 的功能及其向质膜的实际运动，在哺乳动物细胞中尚未完全确定。在这里，我们发现 copines-1、-2、-3、-6 和 -7 在人类胚胎肾细胞系 293 细胞中对乙酰甲胆碱诱导的细胞内钙离子增加的反应不同，并且它们与质膜的结合需要不同水平的细胞内钙离子。我们证明，其中两种 copines 在细胞内钙离子进入后与不同的细胞内囊泡结合，并鉴定出一个新的保守氨基酸序列，该序列是它们在活细胞中质膜易位所必需的。我们的数据表明，Copines 的 von Willebrand 因子 A 结构域调节其对钙离子的敏感性和细胞内靶向性。综上所述，这些发现表明该蛋白家族的成员在介导哺乳动物细胞中钙离子依赖的过程中具有不同的作用。
