Myo1c binds phosphoinositides through a putative pleckstrin homology domain
Myo1c binds phosphoinositides through a putative pleckstrin homology domain
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DOI：
10.1091/mbc.e06-05-0449
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发表时间：
2006-11-01
影响因子：
3.3
通讯作者：
Ostap, E. Michael
中科院分区：
文献类型：
--
作者：
Hokanson, David E.;Laakso, Joseph M.;Ostap, E. Michael
Myo1c是肌球蛋白超家族的一员，可结合磷脂酰肌醇-4,5-二磷酸（PlP2）。将肌动蛋白骨架连接到细胞膜上，在机械信号转导和细胞膜运输中起作用。我们在肌凝蛋白的调控区域和尾部区域内定位并表征了两个不同的膜结合位点。通过序列、二级结构和从头计算分析，我们确定了尾部的一个磷酸肌苷结合位点是一个假定的pleckstrin同源（PH）结构域。已知在先前表征的PH结构域中多磷酸肌苷结合所必需的残基的点突变抑制myo1c与PIP的结合，在体外，破坏体内膜结合，并破坏细胞定位。这个结合位点的延伸序列在其他肌球蛋白- 1亚型中是保守的，表明它们含有这个假定的PH结构域。我们还在IQ基序的调控域中鉴定了先前鉴定的膜结合位点。这个区域不是磷酸肌肽特异性的，但它以钙依赖的方式结合阴离子磷脂。然而，这个位点对体内膜结合并不是必需的。
Myo1c is a member of the myosin superfamily that binds phosphatidylinositol-4,5-bisphosphate (PlP2). links the actin cytoskeleton to cellular membranes and plays roles in mechano-signal transduction and membrane trafficking. We located and characterized two distinct membrane binding sites within the regulatory and tail domains of this myosin. By sequence, secondary structure, and ab initio computational analyses, we identified a phosphoinositide binding site in the tail to be a putative pleckstrin homology (PH) domain. Point mutations of residues known to be essential for polyphosphoinositide binding in previously characterized PH domains inhibit myo1c binding to PIP, in vitro, disrupt in vivo membrane binding, and disrupt cellular localization. The extended sequence of this binding site is conserved within other myosin-I isoforms, suggesting they contain this putative PH domain. We also characterized a previously identified membrane binding site within the IQ motifs in the regulatory domain. This region is not phosphoinositide specific, but it binds anionic phospholipids in a calcium-dependent manner. However, this site is not essential for in vivo membrane binding.