Porter J A, Montell C
Department of Biological Chemistry, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205.
J Cell Biol. 1993 Aug;122(3):601-12. doi: 10.1083/jcb.122.3.601.
The Drosophila ninaC locus encodes a rhabdomere specific protein (p174) with linked protein kinase and myosin domains, required for a wild-type ERG and to prevent retinal degeneration. To investigate the role for linked kinase and myosin domains, we analyzed mutants generated by site-directed mutagenesis. Mutation of the kinase domain resulted in an ERG phenotype but no retinal degeneration. Deletion of the myosin domain caused a change in the subcellular distribution of p174 and resulted in both ERG and retinal degeneration phenotypes. Temperature-sensitive mutations in the myosin domain resulted in retinal degeneration, but no ERG phenotype. These results indicated that the ERG and retinal degeneration phenotypes were not strictly coupled suggesting that the myosin domain has multiple functions. We propose that the role of the kinase domain is to regulate other rhabdomeric proteins important in phototransduction and that the myosin domain has at least two roles: to traffic the kinase into the rhabdomeres and to maintain the rhabdomeres.
果蝇ninaC基因座编码一种横纹小体特异性蛋白（p174），该蛋白具有相连的蛋白激酶和肌球蛋白结构域，是野生型视网膜电图（ERG）所必需的，且能防止视网膜变性。为了研究相连的激酶和肌球蛋白结构域的作用，我们分析了通过定点诱变产生的突变体。激酶结构域的突变导致了ERG表型，但没有视网膜变性。肌球蛋白结构域的缺失导致p174亚细胞分布的改变，并导致ERG和视网膜变性表型。肌球蛋白结构域中的温度敏感突变导致视网膜变性，但没有ERG表型。这些结果表明，ERG和视网膜变性表型并非严格相关，这表明肌球蛋白结构域具有多种功能。我们提出，激酶结构域的作用是调节在光转导中重要的其他横纹小体蛋白，而肌球蛋白结构域至少有两个作用：将激酶运输到横纹小体中以及维持横纹小体。
