Parveen R, Smith J B, Sun Y, Smith D L
Department of Chemistry, Bahauddin Zakariya University, Multan, Pakistan.
J Protein Chem. 1993 Feb;12(1):93-101. doi: 10.1007/BF01024920.
The primary structure and posttranslational modifications of rabbit lens alpha-crystallins were examined using electrospray ionization mass spectrometry to determine the molecular weights of the intact proteins and fast atom bombardment mass spectrometry to analyze proteolytic digests of the alpha A- and alpha B-crystallins. The previously determined primary structure of alpha A-crystallin was confirmed. Posttranslational modifications detected included one phosphorylation site and the presence of a truncated form minus the five C-terminal residues. The previously undetermined amino acid sequence of rabbit alpha B-crystallin was determined to be the same as the bovine alpha B-crystallin sequence except at three residues: Thr 40, Thr 132, and Pro 153. Rabbit alpha B-crystallin showed evidence of phosphorylation at the same three sites as bovine alpha B-crystallin. The molecular weights of the intact proteins indicated that any one molecule had a maximum of two phosphorylations. Also, there was a truncated form which did not include the five C-terminal residues.
利用电喷雾电离质谱法来测定完整蛋白质的分子量，并使用快原子轰击质谱法分析αA-和αB-晶状体蛋白的蛋白水解消化产物，以此来研究兔晶状体α-晶状体蛋白的一级结构和翻译后修饰。先前确定的αA-晶状体蛋白的一级结构得到了证实。检测到的翻译后修饰包括一个磷酸化位点以及一种缺少五个C末端残基的截短形式。确定兔αB-晶状体蛋白先前未确定的氨基酸序列与牛αB-晶状体蛋白序列相同，除了三个残基：苏氨酸40、苏氨酸132和脯氨酸153。兔αB-晶状体蛋白在与牛αB-晶状体蛋白相同的三个位点显示出磷酸化的证据。完整蛋白质的分子量表明任何一个分子最多有两个磷酸化位点。此外，存在一种不包括五个C末端残基的截短形式。
