HIGHLY-ACTIVE SOLUBLE PROCESSED FORMS OF THE TRANSGLUTAMINASE-1 ENZYME IN EPIDERMAL-KERATINOCYTES
HIGHLY-ACTIVE SOLUBLE PROCESSED FORMS OF THE TRANSGLUTAMINASE-1 ENZYME IN EPIDERMAL-KERATINOCYTES
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DOI：
10.1074/jbc.270.30.18026
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发表时间：
1995-07-28
影响因子：
4.8
通讯作者：
STEINERT, PM
中科院分区：
文献类型：
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作者：
KIM, SY;CHUNG, SI;STEINERT, PM
转氨酶1（TGase 1）酶是表皮角质形成细胞中角质形成细胞包膜形成所必需的。我们在这里表明，除了它的膜锚定形式，它的可溶性形式在角质形成细胞中也很重要。分化细胞含有106 kDa的可溶性全长酶，但终末分化细胞也含有通常与33 kDa蛋白质复合的可溶性67 kDa形式。67 kDa形式的氨基末端是TGase 1蛋白的残基93，对应于因子XIIIa TGase的蛋白水解活化位点。33-kDa蛋白质的氨基末端是残基573，对应于因子XIIIa的第二蛋白水解切割位点和TGase 3酶的蛋白水解活化位点。67/33-kDa可溶性复合物的比活性是可溶性67-kDa形式的两倍，是全长TGase 1的10倍。67/33-和106-kDa形式的半衰期分别约为7或20小时。因此，TGase 1酶是复杂的，因为它以多种可溶形式存在于角质形成细胞中，完整或在保守位点蛋白水解加工，并且具有不同的特异性活性和可能的功能。
The transglutaminase 1 (TGase 1) enzyme is required for the formation of a cornified cell envelope in epidermal keratinocytes. We show here that in addition to its membrane-anchored form, soluble forms of it are also important in keratinocytes. Proliferating cells contain soluble full-length enzyme of 106 kDa, but terminally differentiating cells contain a soluble 67-kDa form often complexed with a 33-kDa protein as well. The amino terminus of the 67 kDa form is residue 93 of the TGase 1 protein, corresponding to the site of proteolytic activation of the factor XIIIa TGase. The amino terminus of the 33-kDa protein is residue 573, corresponding to the site of a second proteolytic cleavage site of factor XIIIa, and of the site for proteolytic activation of the TGase 3 enzyme. The specific activity of the 67/33-kDa soluble complex is twice that of the soluble 67-kDa form and 10 times that of full-length TGase 1. The half-lives of the 67/33- and 106-kDa forms are about 7 or 20 h, respectively. Thus the TGase 1 enzyme is complex, since it exists in keratinocytes as multiple soluble forms, either intact or proteolytically processed at conserved sites, and which have varying specific activities and likely functions.