Islam M Khyrul, Alim M Abdul, Tsuji Naotoshi
Department of Global Agricultural Sciences, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo, Japan.
Methods Mol Biol. 2013;963:127-46. doi: 10.1007/978-1-62703-230-8_9.
EF-hand Ca(2+)-binding motif, a structural component of the EF-hand protein, functions as a calcium sensor and/or buffer in the cytosol of the cell. However, in a few exceptional cases, the EF-hand proteins are secreted from cells and play crucial roles extracellularly. We have identified longistatin, an EF-hand Ca(2+)-binding protein, from the salivary glands of the tick, Haemaphysalis longicornis. Longistatin possesses an N-terminal sequence of unknown structure and two EF-hand motifs in the C-terminus, which conserve a calmodulin-like canonical structure. Longistatin shows distinct changes in its migration during electrophoresis through SDS-PAGE gel containing calcium or ethylenediaminetetraacetic acid (EDTA). Both recombinant and endogenous forms of longistatin can be stained with rutheninum red, demonstrating that longistatin is a Ca(2+)-binding protein.
EF 手型钙离子结合基序是 EF 手型蛋白的一种结构成分，在细胞胞质溶胶中作为钙传感器和/或缓冲剂发挥作用。然而，在少数特殊情况下，EF 手型蛋白会从细胞中分泌出来，并在细胞外发挥关键作用。我们从长角血蜱的唾液腺中鉴定出了一种 EF 手型钙离子结合蛋白——长抑素。长抑素在 N 端有一段结构未知的序列，在 C 端有两个 EF 手型基序，它们保留了类似钙调蛋白的典型结构。在含有钙或乙二胺四乙酸（EDTA）的 SDS - PAGE 凝胶中进行电泳时，长抑素的迁移表现出明显变化。重组长抑素和内源性长抑素都能用钌红染色，表明长抑素是一种钙离子结合蛋白。
