ABSTRACT
This chapter presents an overview of stress proteins in Drosophila melanogaster. The stress proteins differ between phyla with regard to type, molecular weight, and expression, but their deoxyribonucleic acid (DNA) sequences show that they belong to one gene family and that they have been highly conserved throughout evolution. Nucleotide homologies between stress proteins in prokaryotes and eukaryotes are 40 to 50% and between stress proteins in eukaryotes are in the range of 70%. The sp70 family is the largest group of stress proteins and plays a central role in defending the cell against stress. The key to the pathway to gene expression of stress proteins, both constitutively present and induced under stressful conditions, is transcription factors, commonly termed heat-shock factors (HSF). The HSFs become activated and bind to upstream DNA sequences of the stress protein genes, called heat-shock elements, thus inducing transcriptional activation of the stress protein genes.
