Karki S, Tokito M K, Holzbaur E L
Cell and Molecular Biology Graduate Group, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania 19104, USA.
J Biol Chem. 1997 Feb 28;272(9):5887-91. doi: 10.1074/jbc.272.9.5887.
We have isolated a 27-kDa protein that binds to cytoplasmic dynein. Microsequencing of a 17-amino acid peptide of this polypeptide yielded a sequence which completely matched the predicted sequence of the beta subunit of casein kinase II, a highly conserved serine/threonine kinase. Affinity chromatography using a dynein column indicates that both the alpha and beta subunits of casein kinase II are retained by the column from rat brain cytosol. Although dynactin is also bound to the column, casein kinase II is not a dynactin subunit. Casein kinase II does not co-immunoprecipitate with dynactin, and it binds to a dynein intermediate chain column which has been preblocked with excess p150(Glued), a treatment that inhibits the binding of dynactin from cytosol. Bacterially expressed and purified rat dynein intermediate chain can be phosphorylated by casein kinase II in vitro. Further, native cytoplasmic dynein purified from rat brain can also be phosphorylated by casein kinase II in vitro. We propose that CKII may be involved in the regulation of dynein function possibly by altering its cargo specificity or its ability to interact with dynactin.
我们分离出了一种与胞质动力蛋白结合的27 kDa蛋白质。对该多肽的一段17个氨基酸的肽段进行微测序，得到的序列与酪蛋白激酶IIβ亚基的预测序列完全匹配，酪蛋白激酶II是一种高度保守的丝氨酸/苏氨酸激酶。使用动力蛋白柱进行亲和层析表明，酪蛋白激酶II的α和β亚基都能被大鼠脑细胞质溶胶中的该柱保留。虽然动力肌动蛋白也与该柱结合，但酪蛋白激酶II不是动力肌动蛋白的亚基。酪蛋白激酶II不能与动力肌动蛋白进行共免疫沉淀，并且它能与已用过量p150（Glued）预先封闭的动力蛋白中间链柱结合，这种处理会抑制动力肌动蛋白从细胞质溶胶中的结合。细菌表达并纯化的大鼠动力蛋白中间链在体外可被酪蛋白激酶II磷酸化。此外，从大鼠脑中纯化的天然胞质动力蛋白在体外也可被酪蛋白激酶II磷酸化。我们提出，酪蛋白激酶II可能通过改变其货物特异性或与动力肌动蛋白相互作用的能力，参与动力蛋白功能的调节。
