Brynda J, Fábry M, Horejsí M, Sedlácek J
Department of Gene Manipulation, Academy of Sciences of the Czech Republic, Prague.
Virology. 1995 Feb 20;207(1):185-90. doi: 10.1006/viro.1995.1065.
Gag-Pol frameshift translational products of avian retroviruses (e.g., myeloblastosis associated virus, MAV) contain a putative proteinase species of 131 amino acids that maps between the NC/PR and the PR/RT processing sites. Expression in Escherichia coli of an in-frame PR precursor that contains the natural NC/PR processing site and is translationally terminated at the PR/RT site leads to formation of a Gag-Pol proteinase of the expected molecular size (131 amino acids) and a novel PR product of 126 amino acids. This product extends 2 amino acids downstream of the gag-encoded 124 amino acids, and its proteolytic cleavage is promoted by conditions favorable for enzyme catalysis, is blocked by a specific MAV proteinase inhibitor, and can be demonstrated also for corresponding peptide substrates. The new self-processing cleavage product is termed PR(+IleGly) and exhibits similar, but slower, catalytic parameters than those of the Gag PR.
禽逆转录病毒（如成髓细胞瘤相关病毒，MAV）的Gag-Pol移码翻译产物包含一种推定的蛋白酶，其由131个氨基酸组成，定位在NC/PR和PR/RT加工位点之间。在大肠杆菌中表达一个读码框内的PR前体，该前体包含天然的NC/PR加工位点，并在PR/RT位点处翻译终止，会导致形成预期分子大小（131个氨基酸）的Gag-Pol蛋白酶和一个由126个氨基酸组成的新型PR产物。该产物在gag编码的124个氨基酸下游延伸2个氨基酸，其蛋白水解切割受到有利于酶催化的条件促进，被一种特异性MAV蛋白酶抑制剂阻断，并且对于相应的肽底物也能得到证实。这种新的自我加工切割产物被称为PR(+IleGly)，其催化参数与Gag PR相似，但速度较慢。
