EPIDERMAL TRANSGLUTAMINASES

转谷氨酰胺酶在受体酰胺之间形成异肽交联物 蛋白质结合的谷氨酰胺残基和蛋白质的供体e-NH2的基团 结合赖氨酸残基，从而形成不溶的大分子蛋白质 很复杂。在表皮中，至少有三种酶起作用。 通过将某些特定的结构蛋白交联而形成角化的 细胞膜，是转谷氨酰胺酶1，2和3。我们正在研究 这些酶的细节。通过使用一种新的特异性抗体，我们发现 培养角质形成细胞或包皮中的转谷氨酰胺酶1酶 表皮细胞是非常复杂的，因为它存在于多种可溶性和 膜结合的全长形式以及蛋白质水解性加工形式。 可溶相和膜相之间的分配由 肉豆蔻酸酯和棕榈酸酯的不同酰化反应。这种酶被广泛使用 在表皮和附属膜结构以及其他组织中表达 非上皮性组织。基因的近端启动子区域 谷氨酰胺转氨酶3基因位于谷氨酰胺转氨酶基因上方的前126个碱基内。 转录起始点，由Sp1基序组成，受 相邻的类ETS图案。这些都足以授予 上皮特异性表达。这个区域还含有一种钙 响应元素。

Transglutaminases form an isopeptide 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 an insoluble macromolecular protein complex. In the epidermis, at least three enzymes are thought to function by crosslinking certain defined structural proteins to form the cornified cell envelope, and are transglutaminases 1, 2 and 3. We are studying these enzymes in detail. By use of a new specific antibody, we have found that the transglutaminase 1 enzyme in cultured keratinocytes or foreskin epidermal cells is very complex, since it exists in multiple soluble and membrane-bound full-length as well as proteolytically- processed forms. The partitioning between the soluble and membrane phases is controlled by differential acylation by myristate and palmitate. The enzyme is widely expressed in the epidermis and appendageal structures, as well as in other non-epithelial tissues. The proximal promoter region of the transglutaminase 3 gene is located within the first 126 bp above the transcription start site, and consists of an Sp1 motif modulated by adjacent ets-like motifs. These are sufficient to confer epithelial-specific expression. This region also contains a calcium responsive element.