Lens transglutaminase and cataract formation.

作者：Laszlo Lorand, L. K. George Hsu, Gerald E. Siefring, Nancy S. Rafferty · 发表于：Proceedings of the National Academy of Sciences · 年份：1981 · DOI：10.1073/pnas.78.3.1356 · 被引用次数：143 · 研究领域：Bee Products Chemical Analysis、Blood properties and coagulation、Pharmacological Effects of Natural Compounds

A protein polymer characteristically present in human cataract was shown to contain significant amounts of gamma-glutamyl-epsilon-lysine isopeptides. It is proposed that these crosslinks are produced by the action of transglutaminase (R-glutaminyl-peptide:amine-gamma-glutamyl-yltransferase, EC 2.3.2.13), which is all the more plausible because lens contains the enzyme and endogenous protein substrates for it. The enzyme is similar to that obtained from liver and is Ca2+ dependent. Highest apparent activity is found in lens cortex. When cortex homogenate from the rabbit was incubated in the presence of Ca2+ with either [14C]putrescine or with dansylcadaverine, a a selective incorporation of the radioactive or fluorescent amine into the heavier subunits (Mr approximately 26,000 and 30,000) of beta-crystallins could be demonstrated. Possible modes of regulating the crosslinking activity of this enzyme in lens are discussed.