Phosphorylation of desmin in vitro inhibits formation of intermediate filaments; identification of three kinase A sites in the aminoterminal head domain.
Phosphorylation of desmin in vitro inhibits formation of intermediate filaments; identification of three kinase A sites in the aminoterminal head domain.
复制标题
体外结蛋白的磷酸化抑制中间丝的形成；
作者：
N. Geisler;K. Weber
分析了 cAMP 依赖性蛋白激酶催化亚基对鸡结蛋白的体外磷酸化。磷酸化结蛋白失去形成中间丝 (IF) 的能力。唯一半胱氨酸的断裂和温和的胰凝乳蛋白酶处理显示三个结构域的磷酸化差异。只有氨基末端头结构域是激酶的靶标。肽分析显示丝氨酸 29 完全磷酸化，而丝氨酸 35 和 50 分别至少被磷酸化 22% 和 50%。所有三个位点均显示序列精氨酸-X-丝氨酸，其中 X 是一个小残基。这些结果强化了这样的观点，即非螺旋头结构域很可能通过其一些精氨酸残基的直接影响对细丝完整性产生强烈影响。结合先前关于激酶 A 磷酸化波形蛋白的结果（Inagaki 等，1987），出现了关于 IF 的新观点。磷酸化可以允许组装和周转中的调节过程。
The in vitro phosphorylation of chicken desmin by the catalytic subunit of cAMP‐dependent protein kinase was analysed. Phosphorylated desmin loses the ability to form intermediate filaments (IFs). Fragmentation at the sole cysteine and mild chymotryptic treatment show a differential phosphorylation of the three structural domains. Only the amino‐terminal head domain is the target of the kinase. Peptide analysis shows that serine 29 is fully phosphorylated, while serine 35 and 50 are phosphorylated at least at 22 and 50% respectively. All three sites show the sequence arginine‐X‐serine with X being a small residue. These results strengthen the view that the nonhelical head domain has a strong influence on filament integrity most likely via a direct influence of some of its arginine residues. Taken together with previous results (Inagaki et al., 1987) on the phosphorylation of vimentin by kinase A, a new view on IFs emerges. Phosphorylation could allow for regulatory processes in assembly and turnover.