Callahan M A, Handley M A, Lee Y H, Talbot K J, Harper J W, Panganiban A T
McArdle Laboratory for Cancer Research, University of Wisconsin Medical School, Madison, Wisconsin 53706, USA.
J Virol. 1998 Jun;72(6):5189-97. doi: 10.1128/JVI.72.6.5189-5197.1998.
Viral protein U (Vpu) is a protein encoded by human immunodeficiency virus type 1 (HIV-1) that promotes the degradation of the virus receptor, CD4, and enhances the release of virus particles from cells. We isolated a cDNA that encodes a novel cellular protein that interacts with Vpu in vitro, in vivo, and in yeast cells. This Vpu-binding protein (UBP) has a molecular mass of 41 kDa and is expressed ubiquitously in human tissues at the RNA level. UBP is a novel member of the tetratricopeptide repeat (TPR) protein family containing four copies of the 34-amino-acid TPR motif. Other proteins that contain TPR motifs include members of the immunophilin superfamily, organelle-targeting proteins, and a protein phosphatase. UBP also interacts directly with HIV-1 Gag protein, the principal structural component of the viral capsid. However, when Vpu and Gag are coexpressed, stable interaction between UBP and Gag is diminished. Furthermore, overexpression of UBP in virus-producing cells resulted in a significant reduction in HIV-1 virion release. Taken together, these data indicate that UBP plays a role in Vpu-mediated enhancement of particle release.
病毒蛋白U（Vpu）是由1型人类免疫缺陷病毒（HIV-1）编码的一种蛋白质，它能促进病毒受体CD4的降解，并增强病毒颗粒从细胞中的释放。我们分离出了一个编码新型细胞蛋白的cDNA，该蛋白在体外、体内及酵母细胞中均能与Vpu相互作用。这种Vpu结合蛋白（UBP）的分子量为41 kDa，在RNA水平上在人体组织中广泛表达。UBP是四肽重复序列（TPR）蛋白家族的一个新成员，包含四个34个氨基酸的TPR基序拷贝。其他含有TPR基序的蛋白包括亲免素超家族成员、细胞器靶向蛋白和一种蛋白磷酸酶。UBP还直接与HIV-1 Gag蛋白相互作用，HIV-1 Gag蛋白是病毒衣壳的主要结构成分。然而，当Vpu和Gag共表达时，UBP与Gag之间的稳定相互作用减弱。此外，在病毒产生细胞中过表达UBP会导致HIV-1病毒体释放显著减少。综上所述，这些数据表明UBP在Vpu介导的颗粒释放增强过程中发挥作用。
