Didichenko S A, Ter-Avanesyan M D, Smirnov V N
Institute of Experimental Cardiology, USSR Cardiology Research Center, Moscow.
Eur J Biochem. 1991 Jun 15;198(3):705-11. doi: 10.1111/j.1432-1033.1991.tb16070.x.
The SUP2 (SUP35) omnipotent suppressor gene encodes the EF-1 alpha-like polypeptide, intimately involved in the control of translational ambiguity in the yeast Saccharomyces cerevisiae. The present study is devoted to the immunological characterization of the Sup2 protein. The SUP2 gene was fused to the Escherichia coli lacZ gene and a polyclonal antibody against the corresponding Sup2--beta-galactosidase hybrid protein was obtained. This antibody identified a 79-kDa protein that was absent in those cells where the SUP2 gene was disrupted, and an abundance of this protein was observed in cells overexpressing the SUP2 gene. The localization of this protein was studied in subcellular fractionation experiments. The SUP2 gene product proved to be uniformly distributed throughout ribosome-enriched samples, i.e. free polysomes, crude microsomes and rough endoplasmic reticulum. It was not found in the cytoplasm and smooth endoplasmic reticulum. The SUP2-encoded protein was fully ribosome associated and less abundant than the ribosomal protein L3. Also, in a sucrose gradient, Sup2 preferentially cosedimented with the 40S ribosomal subunit, but not with the 60S subunit. The functional significance of this association is discussed.
SUP2（SUP35）全能抑制基因编码一种与EF-1α类似的多肽，它与酿酒酵母翻译模糊性的控制密切相关。本研究致力于对Sup2蛋白进行免疫学特性分析。将SUP2基因与大肠杆菌lacZ基因融合，获得了针对相应Sup2-β-半乳糖苷酶杂交蛋白的多克隆抗体。该抗体识别出一种79 kDa的蛋白，在SUP2基因被破坏的细胞中不存在这种蛋白，而在过表达SUP2基因的细胞中观察到该蛋白大量存在。在亚细胞分级分离实验中研究了这种蛋白的定位。结果证明，SUP2基因产物均匀分布于富含核糖体的样品中，即游离多核糖体、粗微粒体和糙面内质网。在细胞质和滑面内质网中未发现该蛋白。SUP2编码的蛋白完全与核糖体结合，且含量低于核糖体蛋白L3。此外，在蔗糖梯度中，Sup2优先与40S核糖体亚基共沉降，而不与60S亚基共沉降。本文讨论了这种结合的功能意义。
