We report the identification of two new members of the Drosophila melanogaster HSP70 gene family, HSC3 and HSC5. DNA sequence analysis predicts that HSC3 encodes a 72-kDa protein with a hydrophobic leader sequence and a C-terminal retrieval tetrapeptide, KDEL, characteristics associated with luminal endoplasmic reticulum (ER) proteins. Sequence analysis predicts that HSC5 encodes a 74-kDa protein with a characteristic mitochondrial leader sequence. We report the deduced amino acid (aa) sequence for the previously identified gene, HSC1. HSC1 encodes a 70-kDa protein lacking a leader sequence and is presumed to have a cytoplasmic localization. A comparison of the deduced aa sequences of these and hsc70 proteins from different species indicates that hsc70 proteins residing in the same intracellular compartment in different organisms are more similar to each other than are hsc70s from the same organism, but different organelles.
