A cDNA presumptively coding for the alpha subunit of the receptor with high affinity for immunoglobulin E.

摘要: Rat mast cells and a neoplastic analogue such as rat basophilic leukemia (RBL) have receptors that exceptionally high affinity for immunoglobulin E (IgE). When aggregated, these induce cellular degranulation. The alpha chain of the receptor contains binding site IgE; function(s) noncovalently associated beta gamma chains is (are) still undefined. Using cDNA library constructed from mRNA RBL cells, we isolated clone whose sequence predicts putative 23-residue signal peptide, followed by accurately amino acid composition, peptide molecular weight, six sequences (encompassing 59 residues or 26% total number) determined direct analysis. These findings provide strong evidence codes chain, even though expression has not been unambiguously achieved. suggests 180-residue extracellular portion with two homologous domains approximately 35 residues, 20-residue transmembrane segment containing an aspartic acid, 27-residue cytoplasmic 9 basic acids. shows no homology low-affinity IgE lymphocytes but over 30% Fc receptor.