Four small Drosophila heat shock proteins are related to each other and to mammalian alpha-crystallin.

Abstract

The primary base sequence of the protein coding regions of the 4 small heat shock genes of D. melanogaster present at cytological locus 67B was determined. A single open reading frame large enough to encode a small heat shock protein is found for each gene. The MW of the predicted proteins are in good agreement with experimentally determined values obtained from gel electrophoresis. The predicted amino acid sequences of the 4 small heat shock genes show striking homologies over .apprxeq. 50% of their lengths. This region of extensive homology extends from about amino acid 85 to amino acid 195 out of a total of .apprxeq. 200 amino acids. Comparison of the predicted sequence with the known sequences of other proteins revealed a remarkable similarity between this region of homology and the corresponding region of mammalian .alpha.-crystallin. The possible functional significance of this structural similarity is discussed.