Reddy T R, Suhasini M, Rappaport J, Looney D J, Kraus G, Wong-Staal F
Department of Medicine, University of California, San Diego, La Jolla 92093-0665, USA.
AIDS Res Hum Retroviruses. 1995 Jun;11(6):663-9. doi: 10.1089/aid.1995.11.663.
The TAt protein of the human immunodeficiency virus type 1 (HIV-1) activates the expression of viral mRNA through a cis-acting element in the LTR termed TAR. TAR RNA forms a stable stem-loop structure. Mutagenesis studies indicate that the stem structure, the primary sequence of the loop, and three unpaired bases in the stem (bulge) are important for Tat activation. Using the in vitro-transcribed TAR RNA as a probe, we have cloned a gene (TARBP-b) that encodes a TAR-binding protein from a cDNA expression library derived from Hut-78 cells. Expression of the 1.4-kb TARBP-b mRNA was observed in all mammalian cell lines tested. TARBP-b binds specifically to the bulge region of TAR RNA and trans-activates the HIV-1 long terminal repeat in the presence of ptat and prev expression plasmids. These results suggest that TARBP-b contributes to tat-mediated trans-activation.
人类免疫缺陷病毒1型（HIV-1）的Tat蛋白通过长末端重复序列（LTR）中一个称为TAR的顺式作用元件激活病毒mRNA的表达。TAR RNA形成一个稳定的茎环结构。诱变研究表明，茎结构、环的一级序列以及茎中的三个未配对碱基（凸起）对Tat激活很重要。利用体外转录的TAR RNA作为探针，我们从Hut-78细胞来源的cDNA表达文库中克隆了一个编码TAR结合蛋白的基因（TARBP-b）。在所有测试的哺乳动物细胞系中均观察到1.4 kb TARBP-b mRNA的表达。TARBP-b特异性结合TAR RNA的凸起区域，并在存在tat和rev表达质粒的情况下反式激活HIV-1长末端重复序列。这些结果表明，TARBP-b有助于tat介导的反式激活。
