The eosinophil-specific cell surface antigen, EOS47, is a chicken homologue of the oncofetal antigen melanotransferrin

摘要: The EOS47 antigen is a 100-kD cell surface glycoprotein selectively expressed by avian retrovirus-transformed eosinophils and their precursors. We have purified the protein to homogeneity used peptide sequence information clone EOS47-encoding cDNAs. open reading frames from these cDNAs predict 738 amino acid with homology human melanotransferrin, membrane-found, transferrin-like that at high levels subset of melanomas, tumor lines, fetal intestine, liver, but not most normal adult tissues. predicted displays 61% identity melanotransferrin conservation all 28 cysteine residues, indicating similar tertiary structure. finding lacks several iron-coordinating acids present in transferrins suggests it may be impaired its ability bind iron. In nonhematopoietic tissues, epithelial brush borders small intestine kidney lower cells lining sinusoids liver. Within hematopoietic restricted subpopulation (1% 5%) bone marrow early spleen fluorescence-activated sorting EOS47+ leads dramatic ( > 30-fold) enrichment peroxidase+ eosinophils. contrast, peripheral blood are EOS47-, suggesting newly formed expression ceases shortly before emigrate into blood. Our results show stage-specific marker should useful for isolation further characterization.