Human lymphocyte Fc receptor for IgE: sequence homology of its cloned cDNA with animal lectins.

We have purified the human lymphocyte Fc receptor specific for IgE (Fc epsilon receptor) and its soluble form by using the anti-Fc epsilon receptor monoclonal antibody H107. Using an oligonucleotide probe corresponding to the partial amino acid sequence of the soluble Fc epsilon receptor related to IgE binding factor, we cloned, sequenced, and expressed a cDNA for the receptor. The Fc epsilon receptor has 321 amino acid residues with no NH2-terminal signal sequence. The receptor was separated into two domains by a putative 24-amino acid residue transmembrane region located near the NH2-terminal end. The Fc epsilon receptor showed a marked homology with animal lectins including human and rat asialoglycoprotein receptors, chicken hepatic lectin, and rat mannose binding proteins.