Kamei A, Iwase H, Masuda K
Department of Biochemistry, Faculty of Pharmaceutical Sciences, Meijo University, Nagoya, Japan.
Biochem Biophys Res Commun. 1997 Feb 13;231(2):373-8. doi: 10.1006/bbrc.1997.6105.
The current study reports for the first time a post-translational modification at the N-terminal region of alpha A- and alpha B-crystallins in normal human lens. The post-translational modification involves a loss of amino acid residues from the N-terminal region. We found three types of losses of N-terminal amino acid(s) from alpha-crystallin. One is the loss of the N-terminal amino acid residues 1-3 from alpha A-crystallin in aged lenses of the age 70 group. The other two modifications were found in alpha B-crystallin. One is the loss of Met(1) of the N-terminus and the other is the loss of 6 amino acids from the N-terminal region. These phenomena were observed in the lenses > 40 age group. Recent studies suggest that the N-terminal region of alpha-crystallin may play a chaperone-like role at the molecular level. These losses of amino acids from the N-terminal region may affect this molecular chaperone-like activity as well as the transparent properties of the human lens.
当前研究首次报道了正常人晶状体中αA-和αB-晶状体蛋白N端区域的一种翻译后修饰。这种翻译后修饰涉及N端区域氨基酸残基的缺失。我们发现α-晶状体蛋白存在三种类型的N端氨基酸缺失。一种是70岁组老年晶状体中αA-晶状体蛋白N端1-3位氨基酸残基的缺失。另外两种修饰存在于αB-晶状体蛋白中。一种是N端甲硫氨酸（1）的缺失，另一种是N端区域6个氨基酸的缺失。这些现象在40岁以上年龄组的晶状体中观察到。最近的研究表明，α-晶状体蛋白的N端区域可能在分子水平上发挥类似伴侣蛋白的作用。N端区域这些氨基酸的缺失可能会影响这种分子伴侣样活性以及人晶状体的透明特性。
