Graduate School of Fisheries Science and Environmental Studies, Nagasaki University, 1-14 Bunkyo, Nagasaki 852-8521, Japan.
Comp Biochem Physiol B Biochem Mol Biol. 2013 Aug;165(4):271-6. doi: 10.1016/j.cbpb.2013.05.007. Epub 2013 Jun 2.
Previously we have isolated a novel gelatinolytic serine proteinase, named G1, from the muscle and the plasma of red sea bream. In order to clarify the structure and function of G1, we cloned the full-length cDNA of G1 from the hepatopancreas of red sea bream. G1 cDNA encoded 633 amino acids with a secretory signal sequence at N-terminus, three epidermal growth factor-like domains, a kringle domain, and a trypsin-like serine protease domain. The active site residues of a serine proteinase were conserved in the serine protease domain of G1. The tissue distributions of the mRNA and gelatinolytic activity of G1 were investigated using RT-PCR and gelatin zymography, respectively. Its activity was detected in various tissues while the mRNA of it was strongly expressed in the hepatopancreas. These results suggest that G1 is synthesized in hepatopancreas and carried to the muscle, kidney, heart and ovary via the bloodstream in the red sea bream. The enzyme has a similar domain structure and tissue distribution to those of human hyaluronan binding protein 2 (HABP2) engaged in the extracellular matrix (ECM) turnover. Thus, it is suggested that G1 is identified as HABP2 and is possibly involved in ECM proteolysis of red sea bream.
先前，我们已经从红鲷鱼的肌肉和血浆中分离出一种新型的明胶酶丝氨酸蛋白酶，命名为 G1。为了阐明 G1 的结构和功能，我们从红鲷鱼的肝胰腺中克隆了 G1 的全长 cDNA。G1 cDNA 编码 633 个氨基酸，在 N 端有一个分泌信号序列，三个表皮生长因子样结构域，一个kringle 结构域和一个胰蛋白酶样丝氨酸蛋白酶结构域。G1 的丝氨酸蛋白酶结构域中的活性位点残基是保守的。使用 RT-PCR 和明胶酶谱法分别研究了 G1 的 mRNA 和明胶酶活性的组织分布。其活性在各种组织中均有检测到，而其 mRNA 在肝胰腺中强烈表达。这些结果表明，G1 在肝胰腺中合成，并通过血流输送到肌肉、肾脏、心脏和卵巢。该酶具有与参与细胞外基质（ECM）周转的人透明质酸结合蛋白 2（HABP2）相似的结构域结构和组织分布。因此，G1 被鉴定为 HABP2，可能参与红鲷鱼的 ECM 蛋白水解。
