Consiglio Nazionale delle Ricerche, Istituto di Biomedicina e Immunologia Molecolare A. Monroy, Via Ugo La Malfa 153, 90146, Palermo, Italy.
Mol Divers. 2010 Nov;14(4):653-65. doi: 10.1007/s11030-009-9203-3. Epub 2009 Nov 12.
The extracellular matrix protein Pl-nectin, a 210-kDa homodimer originally purified from sea urchin eggs, plays a crucial role in cell adhesion and embryonic morphogenesis. The compiled cDNA sequence, obtained by RT-PCR primer walking and 3' RACE, identified a 984aa product containing a 23aa signal peptide and including all six internal peptides identified by protein microsequencing. The protein is a new member of the galactose-binding protein superfamily as it consists of six 151-156aa-long tandemly repeated domains (D1-D6), homologous to the discoidin-like domains, also known as F5/8-type C domains. Based on homology modelling, we present a three-dimensional structure (3D) for D5, identified as the prototype domain. The molecular modelling of the assembled Pl-nectin homodimer accounts for a Pl-nectin quaternary structure composed of two 105-kDa C-shaped monomers linked by a S-S bridge. The presence of an LDT motif between the first and the second exposed loops of the D2 domain suggests the binding of Pl-nectin to an integrin receptor. Altogether, the in silico analysis described here is consistent with previous biochemical reports and offers a basis for predictions to be experimentally tested.
细胞外基质蛋白 Pl- nectin 是一种 210kDa 的同源二聚体，最初从海胆卵中纯化得到，在细胞黏附和胚胎形态发生中发挥着关键作用。通过 RT-PCR 引物行走和 3' RACE 获得的已编译 cDNA 序列，鉴定出一个包含 984 个氨基酸的产物，其中包含一个 23 个氨基酸的信号肽，并包含通过蛋白质微测序鉴定的所有六个内部肽。该蛋白是半乳糖结合蛋白超家族的新成员，因为它由六个 151-156 个氨基酸长的串联重复结构域（D1-D6）组成，与 discoidin 样结构域同源，也称为 F5/8 型 C 结构域。基于同源建模，我们提出了 D5 的三维结构（3D），D5 被鉴定为原型结构域。组装的 Pl-nectin 同源二聚体的分子建模解释了由两个 105kDa C 形单体通过 S-S 桥连接而成的 Pl-nectin 四聚体结构。在 D2 结构域的第一个和第二个暴露环之间存在 LDT 基序，表明 Pl-nectin 与整合素受体结合。总的来说，这里描述的计算机分析与以前的生化报告一致，并为可通过实验测试的预测提供了基础。
