Identification and characterization of molecular interactions between glucose-regulated proteins (GRPs) mortalin/GRP75/peptide-binding protein 74 (PBP74) and GRP94

A heat-shock protein (hsp) 70 family member mortalin/glucose-regulated prot ein (GRP) 75/peptide-binding protein 74 (PBP74) has been localized to vario us cellular compartments including mitochondria, endoplasmic reticulum and cytoplasmic vesicles. Here we describe its interactions with an endoplasmic reticulum protein GRP94, a member of the hsp90 family of GRPs, Interaction s were identified, confirmed and characterized by far-Western screening, in vivo reporter and co-immunoprecipitation assays. Interacting domains of th e two proteins were also characterized by mutational analysis. Such interac tions of these two GRPs may be important for function of either or both and therefore provide important information for further studies.