EPIDERMAL TRANSGLUTAMINASES

转氨酶在受体与受体之间形成异二肽交联， 蛋白质结合的谷氨酰胺残基的酰胺基团和蛋白质结合的谷氨酰胺残基的供体e-NH 2。 蛋白质结合的赖氨酸残基，从而形成高度不溶性的 大分子复合物 在表皮中，三种酶被认为 参与某些确定的结构蛋白的交联， 形成不溶性的皮质细胞被膜，并且是转氨酶1， 2和3 我们正在详细研究人类的角色 转氨酶1和3酶。 通过使用新的特异性抗体，我们 已经发现角质形成细胞中的转氨酶1系统或 包皮表皮是非常复杂的，因为它存在于多个可溶性 以及膜结合形式。 其中最活跃的，67和 33 kDa的复合物通过次级力结合在一起，是在 在这些细胞中的终末分化通过蛋白水解切割， 在转氨酶家族中保守的特定位点。 这类似于已知的蛋白水解激活的蛋白酶。 转氨酶3系统。 基因的近端启动子区 转氨酶3基因位于第一个125 bp以上， 转录起始位点，由Sp1基序组成 由两个相邻的类ETS基序调制。 这些足以 暗示该基因的上皮特异性表达。

Transglutaminases form an isodipeptide crosslink between an acceptor amide group of a protein bound glutamine residue and a donor e-NH2 of a protein bound lysine residue, thereby forming a highly insoluble macromolecular complex. In the epidermis, three enzymes are thought to be involved in crosslinking of certain defined structural proteins to form an insoluble cornified cell envelope, and are transglutaminases 1, 2 and 3. We are studying in detail the roles of the human transglutaminase 1 and 3 enzymes. By use of new specific antibodies, we have found that the transglutaminase 1 system in keratinocytes or foreskin epidermis is very complex, since it exists in multiple soluble as well as membrane-bound forms. The most active of these, a 67 and 33kDa complex held together by secondary forces, is generated during terminal differentiation in these cells by proteolytic cleavage of specific sites that are conserved in the family of transglutaminases. This is similar to the known proteolytic activation of the transglutaminase 3 system. The proximal promoter region of the transglutaminase 3 gene is located within the first 125 bp above the transcription initiation start site, and consists of an Sp1 motif modulated by two adjacent ets-like motifs. These are sufficient to connote epithelial specific expression to this gene.