Chan Y L, Olvera J, Paz V, Wool I G
Department of Biochemistry and Molecular Biology, University of Chicago, Illinois 60637, USA.
Biochem Biophys Res Commun. 1996 Nov 1;228(1):141-7. doi: 10.1006/bbrc.1996.1629.
The amino acid sequence of the rat 40S ribosomal subunit protein S3a was deduced from the sequence of nucleotides in two recombinant cDNAs and confirmed by the determination of the NH2-terminal sequence by Edman degradation. Ribosomal protein S3a has 263 amino acids (the NH2-terminal methionine is removed after translation of the mRNA) and the molecular weight is 29,794. The protein designated S3b has the same amino acid sequence as S3a except that it lacks the carboxyl-terminal 12 residues. We are unable to determine whether there are separate genes for S3a and S3b, or whether there is a single gene and alternate splicing of the precursor to yield separate mRNAs for S3a and S3b, or whether there is a single gene and a single mRNA whose translation yields S3a which is converted by proteolysis, either physiological or fortuitous, to S3b. The mRNA for S3a is about 1000 nucleotides in length. Hybridization of cDNA to digests of nuclear DNA suggests that there are 8-13 copies of the S3a gene. Rat ribosomal protein S3a is identical to the product of the rat Fte-1 gene which encodes the V-Fos transformation effector; S3a is also related to the plant protein cyc07, which is encoded by a cell cycle S-phase specific gene.
大鼠40S核糖体亚基蛋白S3a的氨基酸序列是根据两个重组cDNA中的核苷酸序列推导出来的，并通过埃德曼降解法测定其NH2末端序列得以证实。核糖体蛋白S3a有263个氨基酸（mRNA翻译后NH2末端的甲硫氨酸被去除），分子量为29,794。命名为S3b的蛋白与S3a具有相同的氨基酸序列，只是缺少羧基末端的12个残基。我们无法确定S3a和S3b是由不同的基因产生，还是由一个单一基因通过前体的可变剪接产生分别用于S3a和S3b的不同mRNA，亦或是由一个单一基因和一个单一mRNA产生，其翻译产物为S3a，通过生理或偶然的蛋白水解作用转化为S3b。S3a的mRNA长度约为1000个核苷酸。cDNA与核DNA酶切片段的杂交表明，S3a基因有8 - 13个拷贝。大鼠核糖体蛋白S3a与大鼠Fte - 1基因的产物相同，该基因编码V - Fos转化效应因子；S3a也与植物蛋白cyc07相关，cyc07由细胞周期S期特异性基因编码。
