Members of the Drosophila HSP 70 family share ATP-binding properties

In Drosophila, the hsp 70 family consists of a group of proteins of similar molecular masses (hsps 68, 70 and 72) that exist as multiple isoforms. In this report, it is shown that hsps 68, 70 and 72 from Drosophila cells can be purified by affinity chromatography on ATP-agarose. Furthermore it is demonstrated that the multiple members of the hsp 70 family, which accumulate in large amounts in the nucleus during a heat shock, can be specifically solubilized from the isolated nuclei fraction by ATP. One of the major cognate proteins (hsc 70) also shows similar behavior. These data suggest that most, if not all, of the related Drosophila hsps 70 possess, like their mammalian counterparts, an ATP-binding site which could be related to their function in the stress response.