Cloning and characterization of ovine immunoglobulin G Fc receptor II (FcγRII)

Immunoglobulin G (IgG) Fc receptors (Fc gamma Rs) bind to immune complexes through interactions with the Fc region of IgG to initiate or inhibit the defense mechanism of the leukocytes on which they are expressed. In this study, we describe the cloning, sequencing and characterization of ovine Fc gamma RII. By screening a translated expression sequence tag (EST) database with the protein sequence of bovine IgG Fc receptor II, we identified a putative ovine homologue. Using rapid amplification of cDNA ends (RACE), we isolated the cDNA encoding ovine Fc gamma RII from peripheral blood leucocyte RNA. The ovine Fc gamma RII cDNA contains an 894 bp open-reading frame, encoding a 297 amino acid transmembrane glycoprotein composed of two immunoglobulin-like extracellular domains, a transmembrane region and a cytoplasmic tail with an immunoreceptor tyrosine-based inhibitory motif (ITIM). The glycoprotein encoded by the cloned cDNA was then expressed on the surface of COS-7 cells and immunoglobulin-binding assays show that it binds ovine IgG1, but not IgG2. Identification of the ovine Fc gamma RII will aid in the understanding of the molecular basis of IgG-Fc gamma R interaction. (C) 2009 Elsevier B.V. All rights reserved.