Berbers G A, Feenstra R W, van den Bos R, Hoekman W A, Bloemendal H, de Jong W W
Proc Natl Acad Sci U S A. 1984 Nov;81(22):7017-20. doi: 10.1073/pnas.81.22.7017.
A Ca2+-dependent transglutaminase (EC 2.3.2.13) has been demonstrated in the eye lenses of several mammalian species [Lorand, L., Hsu, L. K. M., Siefring, G. E., Jr., & Rafferty, N. S. (1981) Proc. Natl. Acad. Sci. USA 78, 1356-1360]. Using [3H]methylamine as a convenient probe for transglutaminase activity, we have explored the action of this enzyme in the bovine eye lens. We could characterize the glutamine residues acting as acyl-donor sites in three beta-crystallin chains, which are the only substrates for lens transglutaminase among the various lens-specific structural proteins, the crystallins. A single glutamine was found to bind [3H]methylamine in each of these three chains: glutamine -9 in beta Bp (beta B2), glutamine -21 in beta B3, and glutamine -23 or -24 in beta A3. The four glutamines are all located in the NH2-terminal regions, which presumably extend from the compact two-domain structure of the beta-crystallin chains. It was, moreover, established that several components of the lens cytoskeleton are substrates for transglutaminase.
在几种哺乳动物的眼晶状体中已证实存在一种钙依赖性转谷氨酰胺酶（EC 2.3.2.13）[洛兰德，L.，许，L.K.M.，西弗林，G.E.，Jr.，&拉弗蒂，N.S.（1981年）《美国国家科学院院刊》78，1356 - 1360]。使用[³H]甲胺作为转谷氨酰胺酶活性的便捷探针，我们研究了该酶在牛眼晶状体中的作用。我们能够确定在三条β - 晶状体蛋白链中作为酰基供体位点的谷氨酰胺残基，这三条链是晶状体特异性结构蛋白（晶状体蛋白）中晶状体转谷氨酰胺酶的唯一底物。在这三条链中的每一条链上都发现有一个谷氨酰胺结合[³H]甲胺：βBp（βB2）中的谷氨酰胺 - 9、βB3中的谷氨酰胺 - 21以及βA3中的谷氨酰胺 - 23或 - 24。这四个谷氨酰胺都位于NH₂ - 末端区域，该区域大概从β - 晶状体蛋白链紧密的双结构域结构延伸出来。此外，还确定晶状体细胞骨架的几个成分是转谷氨酰胺酶的底物。
