Park C G, Jung M Y, Choi Y, Winslow G M
Rockefeller University, New York 10021, USA.
J Exp Med. 1995 May 1;181(5):1899-904. doi: 10.1084/jem.181.5.1899.
The mouse mammary tumor virus-7 superantigen (vSAG7) is proteolytically processed in B cells at as many as three positions. Proteolytic processing appears to be important for superantigen activity because a processed form of vSAG7 was predominant among those forms that were found to bind to major histocompatibility complex class II molecules. To determine the functional significance of proteolytic processing, a mutation was introduced in vSAG7 at one of the sites where proteolytic cleavage is thought to take place in B cells. Elimination of the putative processing site at position 171 abrogated detectable vSAG7 surface expression in B cells, indicating that proteolytic processing is required for vSAG7 function. Coexpression in insect cells of vSAG7 and furin, a proprotein-processing enzyme, also demonstrated that furin could process vSAG7 at position 171.
小鼠乳腺肿瘤病毒-7超抗原（vSAG7）在B细胞中多达三个位点进行蛋白水解加工。蛋白水解加工似乎对超抗原活性很重要，因为在那些被发现能与主要组织相容性复合体II类分子结合的vSAG7形式中，加工后的形式占主导地位。为了确定蛋白水解加工的功能意义，在vSAG7中引入了一个突变，该突变位于B细胞中被认为发生蛋白水解切割的位点之一。消除171位的假定加工位点消除了B细胞中可检测到的vSAG7表面表达，表明蛋白水解加工是vSAG7功能所必需的。vSAG7与前体蛋白加工酶弗林蛋白酶在昆虫细胞中的共表达也表明，弗林蛋白酶可以在171位加工vSAG7。
