Analysis of the factors involved in the loss and restoration of the chaperone-like function of alpha-crystallin.
Analysis of the factors involved in the loss and restoration of the chaperone-like function of alpha-crystallin.
复制标题
α-晶状体蛋白伴侣样功能丧失和恢复的相关因素分析。
DOI：
10.1006/bbrc.1997.6079
复制
发表时间：
1997
期刊：
影响因子：
--
通讯作者：
Reid,GH
中科院分区：
文献类型：
--
作者：
Koretz,JF;Doss,EW;Reid,GH
α-晶状体蛋白是哺乳动物眼睛晶状体的主要蛋白质成分，在体内作为两种独立的基因产物被发现。两种亚型均在身体的不同主要组织中表达，晶状体是两者同时存在的唯一位置。两个序列都可以被磷酸化，尽管在不同的位置。两者都与小热休克蛋白表现出高度的序列同源性，并且已表明 α-晶状体蛋白也能抵抗热诱导的变性。霍维茨[J.霍洛维茨 (1992)Proc。国家。阿卡德。科学。 USA89, 10449–10453]证明α-晶状体蛋白可以表现出类似伴侣的保护作用，防止热引起的浊度增加，并且有人认为这也可能是一种体内功能。然而，除了一种磷酸化物种外，两种同工型在纯化后都没有表现出与本地物种相同的伴侣样活性总体水平。 A. M. van Boekel、S. E. A. Hoogakker、J. J. Harding 和 W. W. de Jong（1996）眼科研究 28（增刊 1），32-38]。旨在确定导致分子伴侣样活性丧失的因素的实验表明，强离子条件（例如同工型分离中使用的条件和/或二价阳离子的存在）会降低该功能的效率，并且无论先前的处理或缓冲条件如何，EDTA 的存在都会完全恢复该功能。在所有条件下基本上都能保持热稳定性。这些结果表明，α-晶状体蛋白可能主要在体内充当热休克蛋白，并且其伴侣样功能可能在生理条件下受到抑制。
α-crystallin, the major protein component of the crystallin lens of mammalian eyes, is foundin vivoas two separate gene products. Both isoforms are expressed in different major tissues of the body, with the lens the only location where both are found together. Both sequences can be phosphorylated, though at different locations. Both exhibit a high sequence homology to the small heat shock proteins, and it has been shown that α-crystallin also resists heat-induced denaturation. Horwitz [J. Horowitz (1992)Proc. Natl. Acad. Sci. USA89, 10449–10453] demonstrated that α-crystallin can exhibit chaperone-like protection against heat-induced turbidity increases, and it has been suggested that this may be anin vivofunction as well. However, neither isoform, when purified, shows the same overall level of chaperone-like activity as the native species, except for one phosphorylated species [M. A. M. van Boekel, S. E. A. Hoogakker, J. J. Harding, and W. W. de Jong (1996)Ophthalmic Res.28(Suppl. 1), 32–38]. Experiments designed to determine the factors leading to loss of chaperone-like activity indicate that strong ionic conditions, such as those used in isoform separation and/or the presence of divalent cations reduce the efficiency of this function and that the presence of EDTA fully restores it irrespective of prior treatment or buffer conditions. Heat stabilty is essentially preserved under all conditions. These results suggest that α-crystallin may serve primarily as a heat shock proteinin vivoand that the chaperone-like function may be inhibited under physiological conditions.