EXPRESSION CLONING OF A HUMAN FC RECEPTOR FOR IGA

IgA, the predominant isotype in secretions, mediates the neutralization and removal ofenvironmental antigens from mucosal sites. Although cell surface receptors for the Fc region of IgA (FcαR) have been implicated in a variety ofimmune effector mechanisms, the molecular features ofFcaR remain only marginally characterized. In this report, we describe the isolation of a clone from a myeloid cell line cDNA library that directs the expression of a cell surface molecule with IgA binding specificity. The cDNA encodes a peptide of Mr 30,000 including a putative transmembrane region with features atypical ofconventional membrane-anchored proteins. Databank searches indicate that the human myeloid cell FcaR sequence is unique, is a member of the immunoglobulin gene superfamily, and is related to Fc receptors for IgG (FcγRI, II, and III) and IgE (Fcϵ-RI). © 1990, Rockefeller University Press., All rights reserved.