Bone morphogenetic protein 1 is an extracellular processing enzyme of the laminin 5 γ2 chain
Bone morphogenetic protein 1 is an extracellular processing enzyme of the laminin 5 γ2 chain
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DOI：
10.1074/jbc.m002345200
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发表时间：
2000-07-28
影响因子：
4.8
通讯作者：
Burgeson, RE
中科院分区：
文献类型：
--
作者：
Amano, S;Scott, IC;Burgeson, RE
维持在含有低钙的培养基中的上皮细胞在α 3和γ 2链内蛋白水解处理层粘连蛋白5（α 3 β 3 γ 2）（1）。设计实验以鉴定负责层粘连蛋白5加工的酶和蛋白水解切割的位点。为了表征层粘连蛋白5加工的性质，我们确定了由加工事件产生的蛋白水解片段的N-末端氨基酸序列。结果表明，第一个α 3链裂解（200-165 kDa α 3）发生在G结构域的亚结构域G4内。第二次切割（165-145 kDa α 3）发生在Ina结构域内，11个残基N-末端到结构域II的起始处。γ链在结构域III的第二个表皮生长因子样重复序列内裂解。γ 2链内切割的序列与骨形态发生蛋白-1（BMP-1）（也称为I型前胶原C蛋白酶）切割I型、II型和III型前胶原的共有序列相匹配（2）。重组BMP-1在体外切割γ 2，在完整的层粘连蛋白5内和重组γ 2短臂的预测位点。α 3也被BMP-1在体外切割，但切割位点尚未确定。这些结果表明层粘连蛋白α 3和γ 2链是体外BMP-1的底物。我们推测γ 2裂解是形成层粘连蛋白5-6复合物所必需的。并且该复合物直接参与半桥粒间基底膜的组装。这进一步表明，BMP-1活性促进体内富含层粘连蛋白5的真皮-表皮连接基底膜中的基底膜组装，但不促进半桥粒组装。
Epithelial cells maintained in culture medium containing low calcium proteolytically process laminin 5 (alpha 3 beta 3 gamma 2) within the alpha 3 and gamma 2 chains (1). Experiments were designed to identify the enzyme(s) responsible for the laminin 5 processing and the sites of proteolytic cleavage. To characterize the nature of laminin 5 processing, we determined the N-terminal amino acid sequences of the proteolytic fragments produced by the processing events. The results indicate that the first alpha 3 chain cleavage (200-165 kDa alpha 3) occurs within subdomain G4 of the G domain. The second cleavage (165-145 kDa alpha 3) occurs within the Ina domain, 11 residues N-terminal to the start of domain II. The gamma chain is cleaved within the second epidermal growth factor-like repeat of domain III. The sequence cleaved within the gamma 2 chain matches the consensus sequence for the cleavage of type I, II, and III procollagens by bone morphogenetic protein-1 (BMP-1), also known as type I procollagen C-proteinase (2). Recombinant BMP-1 cleaves gamma 2 in vitro, both within intact laminin 5 and at the predicted site of a recombinant gamma 2 short arm. alpha 3 is also cleaved by BMP-1 in vitro, but the cleavage site is yet to be determined. These results show the laminin alpha 3 and gamma 2 chains to be substrates for BMP-1 in vitro. We speculate that gamma 2 cleavage is required for formation of the laminin 5-6 complex. and that this complex is directly involved in assembly of the interhemidesmosomal basement membrane. This further suggests that BMP-1 activity facilitates basement membrane assembly, but not hemidesmosome assembly, in the laminin 5-rich dermal-epidermal-junction basement membrane in vivo.