Aguilar Rubén Claudio, Watson Hadiya A, Wendland Beverly
Department of Biology, The Johns Hopkins University, Baltimore, Maryland 21218, USA.
J Biol Chem. 2003 Mar 21;278(12):10737-43. doi: 10.1074/jbc.M211622200. Epub 2003 Jan 14.
In addition to its well known role in targeting proteins for proteasomal degradation, ubiquitin (Ub) is also involved in promoting internalization of cell surface proteins into the endocytic pathway. Moreover, putative Ub interaction motifs (UIMs) as well as Ub-associated (UBA) domains have been identified in key yeast endocytic proteins (the epsins Ent1 and Ent2, and the Eps15 homolog Ede1). In this study, we characterized the interaction of Ub with the Ede1 UBA domain and with the UIMs of Ent1. Our data suggest that the UIMs and the UBA are involved in binding these proteins to biological membranes. We also show that the Ent1 ENTH domain binds to phosphoinositides in vitro and that Ent1 NPF motifs interact with the EH domain-containing proteins Ede1 and Pan1. Our findings indicate that the ENTH domain interaction with membrane lipids cooperates with the binding of membrane-associated Ub moieties. These events may in turn favor the occurrence of other interactions, for instance EH-NPF recognition, thus stabilizing networks of low affinity binding partners at endocytic sites.
除了在将蛋白质靶向蛋白酶体降解方面的知名作用外，泛素（Ub）还参与促进细胞表面蛋白内化进入内吞途径。此外，在关键的酵母内吞蛋白（epsin蛋白Ent1和Ent2以及Eps15同源物Ede1）中已鉴定出假定的泛素相互作用基序（UIM）以及泛素相关（UBA）结构域。在本研究中，我们表征了泛素与Ede1 UBA结构域以及Ent1的UIM之间的相互作用。我们的数据表明，UIM和UBA参与将这些蛋白质与生物膜结合。我们还表明，Ent1的ENTH结构域在体外与磷酸肌醇结合，并且Ent1的NPF基序与含EH结构域的蛋白质Ede1和Pan1相互作用。我们的研究结果表明，ENTH结构域与膜脂的相互作用与膜相关泛素部分的结合协同作用。这些事件可能反过来有利于其他相互作用的发生，例如EH-NPF识别，从而稳定内吞位点处低亲和力结合伙伴的网络。
