Cloning and characterization of human erythroid membrane-associated protein, human ERMAP

We describe here the cloning and characterization of the human gene ERMAP, identified by subtractive hybridization using early and late gestation huma n fetal liver. By in situ hybridization, we found human ERMAP to be express ed not only in erythoid cells in fetal liver and adult bone marrow, but als o in reticulocytes and circulating erythroblasts in 8-12-week fetal cord bl ood. The human ERMAP protein is predicted to contain a transmembrane segmen t and one extracellular immunoglobulin fold (IgV). The cytoplasmic region c ontains a highly conserved B30.2 motif, multiple consensus sequences for ki nases, and post-Golgi sorting signals. The protein was localized to the cel l surface as shown by an antibody specific for a peptide predicted from the IgV fold. The amino acid sequence of human ERMAP is highly homologous with that of mouse ERMAP, but differs in the number of extracellular immunoglob ulin folds. Human ERMAP represents a new unique member of the rapidly growi ng B30.2 domain proteins.