Identification of eukaryotic parvulin homologues:: A new subfamily of peptidylprolyl cis-trans isomerases

We report here the existence of a subfamily of eukaryotic parvulin proteins that have strong sequence homology with E. coli parvulin, but lack the WW do. main found in previously described eukarytoic parvulins. We hence term members of this subfamily EPVH (eukaryotic parvulin homologue). We describe the characterisation of hEPVH (human eukaryotic parvulin homologue). Immunogold labelling transmission electron microscopy reveals that hEPVH is preferentially localised in the mitochondrial matrix. The homology of hEPVH with its prokaryotic ancestor supports the hypothesis that this protein may have a mitochondrial function. An essential role in this organelle may explain the need for a high degree of conservation of this protein between distantly related species. (C) 1999 Academic Press.