Caughey G H, Zerweck E H, Vanderslice P
Cardiovascular Research Institute, University of California, San Francisco 94143-0911.
J Biol Chem. 1991 Jul 15;266(20):12956-63.
A gene encoding human chymase was cloned and sequenced. The protein-coding exons reveal a preproenzyme with a 19-amino acid signal peptide, an acidic 2-amino acid propeptide, and a 226-amino acid catalytic domain. The mature enzyme is predicted to be cationic (net charge of +13) and to be modified by N-glycosylation at two sites. The amino acid sequence is identical to the 35 residues of NH2-terminal amino acid sequence reported for human skin chymase and is identical to 29 of 31 residues of NH2-terminal and internal amino acid sequence reported for human heart chymase. The full predicted sequence of the catalytic domain reveals a high level of sequence identity to dog mast cell chymase (83%) and a lower level of identity to the sequences of rodent chymases (58-62%). In the phase and placement of introns, the organization of this human chymase gene is similar to that of several other granule-associated leukocyte serine proteases, including rat chymase II, lymphocyte granzymes, and neutrophil cathespin G and elastase. However, the gene organization differs from that of mast cell tryptase, providing additional evidence that the major mast cell serine proteases are separated by substantial evolutionary distance. Amplification of chymase gene-specific fragments from hamster/human hybrid cell line DNA suggests localization of the chymase gene to human chromosome 14. High stringency hybridization of chymase DNA to a human genomic DNA blot suggests the possibility of more than one human chymase gene. Evidence that the chymase gene is expressed in human tissues was obtained by the amplification of chymase-specific DNA from skin and placental cDNA libraries.
编码人糜酶的基因被克隆并测序。蛋白质编码外显子显示一个前原酶，其具有19个氨基酸的信号肽、2个氨基酸的酸性前肽和226个氨基酸的催化结构域。预测成熟酶为阳离子型（净电荷为 +13），并在两个位点进行N - 糖基化修饰。氨基酸序列与人皮肤糜酶报道的NH2末端35个氨基酸序列相同，与人心脏糜酶报道的NH2末端和内部31个氨基酸序列中的29个相同。催化结构域的完整预测序列显示与犬肥大细胞糜酶有高度的序列同一性（83%），与啮齿动物糜酶序列的同一性较低（58 - 62%）。在基因内含子的阶段和位置方面，该人糜酶基因的组织与其他几种颗粒相关白细胞丝氨酸蛋白酶相似，包括大鼠糜酶II、淋巴细胞颗粒酶、中性粒细胞组织蛋白酶G和弹性蛋白酶。然而，基因组织与肥大细胞类胰蛋白酶不同，这提供了额外的证据，表明主要的肥大细胞丝氨酸蛋白酶在进化上有很大的距离。从仓鼠/人杂交细胞系DNA扩增糜酶基因特异性片段表明糜酶基因定位于人类染色体14。糜酶DNA与人基因组DNA印迹的高严谨度杂交表明可能存在不止一个人糜酶基因。通过从皮肤和胎盘cDNA文库中扩增糜酶特异性DNA，获得了糜酶基因在人体组织中表达的证据。
