Hunt C, Morimoto R I
Proc Natl Acad Sci U S A. 1985 Oct;82(19):6455-9. doi: 10.1073/pnas.82.19.6455.
We have determined the nucleotide sequence of the human hsp70 gene and 5' flanking region. The hsp70 gene is transcribed as an uninterrupted primary transcript of 2440 nucleotides composed of a 5' noncoding leader sequence of 212 nucleotides, a 3' noncoding region of 242 nucleotides, and a continuous open reading frame of 1986 nucleotides that encodes a protein with predicted molecular mass of 69,800 daltons. Upstream of the 5' terminus are the canonical TATAAA box, the sequence ATTGG that corresponds in the inverted orientation to the CCAAT motif, and the dyad sequence CTGGAAT/ATTCCCG that shares homology in 12 of 14 positions with the consensus transcription regulatory sequence common to Drosophila heat shock genes. Comparison of the predicted amino acid sequences of human hsp70 with the published sequences of Drosophila hsp70 and Escherichia coli dnaK reveals that human hsp70 is 73% identical to Drosophila hsp70 and 47% identical to E. coli dnaK. Surprisingly, the nucleotide sequences of the human and Drosophila genes are 72% identical and human and E. coli genes are 50% identical, which is more highly conserved than necessary given the degeneracy of the genetic code. The lack of accumulated silent nucleotide substitutions leads us to propose that there may be additional information in the nucleotide sequence of the hsp70 gene or the corresponding mRNA that precludes the maximum divergence allowed in the silent codon positions.
我们已经测定了人类hsp70基因及其5'侧翼区域的核苷酸序列。hsp70基因转录生成一个2440个核苷酸的不间断初级转录本，它由一个212个核苷酸的5'非编码前导序列、一个242个核苷酸的3'非编码区域以及一个1986个核苷酸的连续开放阅读框组成，该开放阅读框编码一种预测分子量为69,800道尔顿的蛋白质。在5'末端上游有典型的TATAAA框、与CCAAT基序反向对应的ATTGG序列，以及与果蝇热休克基因共有的共有转录调控序列在14个位置中的12个位置具有同源性的二元序列CTGGAAT/ATTCCCG。将人类hsp70的预测氨基酸序列与已发表的果蝇hsp70和大肠杆菌dnaK的序列进行比较，发现人类hsp70与果蝇hsp70的同一性为73%，与大肠杆菌dnaK的同一性为47%。令人惊讶的是，人类和果蝇基因的核苷酸序列同一性为72%，人类和大肠杆菌基因的同一性为50%，鉴于遗传密码的简并性，这种保守程度高于必要水平。缺乏累积的沉默核苷酸替换使我们提出，hsp70基因或相应mRNA的核苷酸序列中可能存在额外信息，排除了沉默密码子位置允许的最大差异。
