Research
Membrane-bound progesterone receptors contain a cytochrome b5-like ligand-binding domain
1 The Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Hinxton CB10 1SA, UK
2 University of Malta Medical School, Saint Luke's Hospital, Guardamangia Hill, Guardamangia MSD 09, Malta
Genome Biology 2002, 3:research0068-research0068.5 doi:10.1186/gb-2002-3-12-research0068
Published: 12 November 2002Abstract
Background
Membrane-associated progesterone receptors (MAPRs) are thought to mediate a number of rapid cellular effects not involving changes in gene expression. They do not show sequence similarity to any of the classical steroid receptors. We were interested in identifying distant homologs of MAPR better to understand their biological roles.
Results
We have identified MAPRs as distant homologs of cytochrome b5. We have also found regions homologous to cytochrome b5 in the mammalian HERC2 ubiquitin transferase proteins and a number of fungal chitin synthases.
Conclusions
In view of these findings, we propose that the heme-binding cytochrome b5 domain served as a template for the evolution of membrane-associated binding pockets for non-heme ligands.
