Tanaka J, Ogawara M, Ando S, Shibata M, Yatani R, Kusagawa M, Inagaki M
Department of Neurophysiology, Tokyo Metropolitan Institute of Gerontology, Japan.
Biochem Biophys Res Commun. 1993 Oct 15;196(1):115-23. doi: 10.1006/bbrc.1993.2223.
A 62 kd protein was purified from the Triton-insoluble fraction of porcine brain white matter. This protein formed 10nm filaments, in vitro. The phosphorylation of the 62 kd protein by cAMP-dependent protein kinase caused electrophoretic mobility to shift to 66 kd on SDS-PAGE and a complete loss of the filament forming ability ensued. Amino acid sequences of four peptide fragments obtained from the 62 kd protein by lysylendopeptidase were identical with that of a 66 kd rat brain alpha-internexin. Amino acid analyses of the phosphopeptide fragment derived from phosphorylated porcine alpha-internexin revealed that the phosphorylation sites by cAMP-dependent protein kinase located in the amino-terminal head domain of this protein. These results strongly suggest that alpha-internexin polymerizes into 10nm filaments in vitro and that phosphorylation of the amino-terminal domain of alpha-internexin controls its polymerizability.
从猪脑白质的 Triton 不溶性部分纯化出一种 62 kd 的蛋白质。该蛋白质在体外形成 10nm 的细丝。cAMP 依赖性蛋白激酶对 62 kd 蛋白质的磷酸化导致其在 SDS-PAGE 上的电泳迁移率变为 66 kd，随后细丝形成能力完全丧失。通过赖氨酰内肽酶从 62 kd 蛋白质获得的四个肽片段的氨基酸序列与 66 kd 大鼠脑α-中间丝蛋白的序列相同。对磷酸化猪α-中间丝蛋白衍生的磷酸肽片段的氨基酸分析表明，cAMP 依赖性蛋白激酶的磷酸化位点位于该蛋白质的氨基末端头部结构域。这些结果有力地表明，α-中间丝蛋白在体外聚合成 10nm 的细丝，并且α-中间丝蛋白氨基末端结构域的磷酸化控制其聚合能力。
