Drosophila gene related to the major heat shock-induced gene is transcribed at normal temperatures and not induced by heat shock.

A gene related to the major heat shock-induced (hsp70) gene of Drosophila has been isolated from the sibling species D. melanogaster and D. simulans. This heat shock-cognate (hsc70) gene is present at cytological locus 70C. The primary sequence of approximately one-third of the protein-coding region has been compared with that of the hsp70 gene; 72% homology of the base sequence and 74% homology of the deduced amino acid sequence was found. In the codon specifying amino acid 66, the hsc70 gene contains an insertion of 1.7 kilobases; the hsp70 genes contain no intervening sequences. The sequence at the 5' and 3' junctions of the insertion is similar to that found in many intervening sequences. cDNA extension experiments indicate that the hsc70 gene is transcribed at normal temperatures in adult flies and that transcription is not enhanced by heat treatment.