Burd C G, Emr S D
Howard Hughes Medical Institute, University of California, San Diego School of Medicine, La Jolla 92093-0668, USA.
Mol Cell. 1998 Jul;2(1):157-62. doi: 10.1016/s1097-2765(00)80125-2.
Phosphoinositide 3-kinases (PI(3)K) are important regulators of receptor signaling cascades and intracellular membrane trafficking. To date, no protein domain has been identified that binds specifically to Ptdlns(3)P and thereby recruits/activates downstream effectors of Ptdlns(3)P signaling. Using an in vivo assay in yeast that detects Vps34 PI(3)K-dependent intracellular localization of a GFP reporter protein, and in vitro lipid-binding assays, we demonstrate that cysteine-rich RING domains of the FYVE finger subfamily bind specifically to Ptdlns phosphorylated exclusively at the D-3 position of the inositol ring. GFP-FYVE domain fusion proteins localized predominantly to membranes of endocytic compartments and required active Vps34 PI(3)K. Our data establish a molecular link between Vps34 PI(3)K and several FYVE domain-containing proteins (Vac1p, Vps27p) required for vacuolar/lysosomal protein trafficking.
磷酸肌醇3激酶（PI(3)K）是受体信号级联反应和细胞内膜运输的重要调节因子。迄今为止，尚未发现能特异性结合磷脂酰肌醇-3-磷酸（Ptdlns(3)P）并因此招募/激活Ptdlns(3)P信号下游效应器的蛋白质结构域。利用酵母体内检测绿色荧光蛋白（GFP）报告蛋白的Vps34 PI(3)K依赖性细胞内定位的试验以及体外脂质结合试验，我们证明了FYVE指亚家族富含半胱氨酸的RING结构域特异性结合仅在肌醇环D-3位磷酸化的Ptdlns。GFP-FYVE结构域融合蛋白主要定位于内吞区室的膜上，并且需要活性Vps34 PI(3)K。我们的数据建立了Vps34 PI(3)K与液泡/溶酶体蛋白运输所需的几种含FYVE结构域的蛋白质（Vac1p、Vps27p）之间的分子联系。
