Laber B, Krieglstein K, Henschen A, Kos J, Turk V, Huber R, Bode W
Max-Planck-Institut für Biochemie, Martinsried, FRG.
FEBS Lett. 1989 May 8;248(1-2):162-8. doi: 10.1016/0014-5793(89)80453-3.
Peptide maps obtained by reversed-phase HPLC of tryptic digests of isoelectric form 1 (pI = 6.5) and 2 (pI = 5.6) of chicken egg white cystatin revealed that the difference was located only in a single peptide (residues Ser-74-Lys-91). Ser-80 of cystatin 2 was subsequently identified as being modified by phosphorylation. Moreover, alkaline phosphatase treatment of a mixture of native cystatin forms 1 and 2 was shown by ion-exchange chromatography to cause the disappearance of isoelectric form 2 with a concomitant increase in form 1. Thus, the existence of two isoelectric forms of chicken cystatin is due to the phosphorylated form 2 and non-phosphorylated form 1.
通过反相高效液相色谱法对鸡卵类黏蛋白等电形式1（pI = 6.5）和2（pI = 5.6）的胰蛋白酶消化产物进行肽图谱分析，结果表明差异仅存在于单个肽段（Ser-74-Lys-91残基）中。随后鉴定出类黏蛋白2的Ser-80被磷酸化修饰。此外，离子交换色谱法显示，用碱性磷酸酶处理天然类黏蛋白形式1和2的混合物会导致等电形式2消失，同时形式1增加。因此，鸡类黏蛋白两种等电形式的存在是由于磷酸化的形式2和未磷酸化的形式1。
