A novel activating chicken IgY FcR is related to leukocyte receptor complex (LRC) genes but is located on a chromosomal region distinct from the LRC and FcR gene clusters.
FcRs have multifaceted roles in the immune system. Chicken FcRs were demonstrated on macrophages decades ago; however, only recently the chicken Ig-like receptor AB1, encoded in the leukocyte receptor complex, was molecularly identified as a high-affinity FcR. The present study was initiated to identify additional receptors with the capability to bind chicken immunoglobulins. Based on database searches, we cloned a novel chicken FcR, designated gallus gallus FcR (ggFcR), which was shown to bind selectively chicken IgY. The receptor consists of four extracellular C2-set Ig domains, followed by a transmembrane region containing arginine as a positively charged amino acid and a short cytoplasmic tail. ggFcR associates with the common gamma-chain, indicative for an activating receptor, and real-time RT-PCR revealed high expression on PBMC, thrombocytes, and macrophages. The genomic organization is similar to most Ig-like receptor genes, where each Ig domain is encoded by a separate exon. Additionally, the ggFcR signal peptide is encoded by two exons, the second of which is 36 bp, a hallmark for genes encoded in the leukocyte receptor complex. Phylogenetic analysis also showed a relationship to genes encoded in the leukocyte receptor complex. Surprisingly, ggFcR is not encoded in the leukocyte receptor complex, but it is located as a single isolated gene at the extremity of chicken chromosome 20.
Viertlboeck
Birgit C
BC
Institute for Animal Physiology, University of Munich, Munich, Germany. Birgit.Viertlboeck@lmu.de
Schmitt
Ramona
R
Hanczaruk
Matthias A
MA
Crooijmans
Richard P M A
RP
Groenen
Martien A M
MA
Göbel
Thomas W
TW
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D001666:Binding Sites, Antibody / Q000235:genetics; D002460:Cell Line; D045744:Cell Line, Tumor; D002645:Chickens / Q000235:genetics / Q000276:immunology*; D003001:Cloning, Molecular; D006801:Humans; D007136:Immunoglobulins / Q000235:genetics / Q000378:metabolism* / Q000502:physiology; D007962:Leukocytes / Q000276:immunology* / Q000378:metabolism; D008213:Lymphocyte Activation / Q000235:genetics* / Q000276:immunology; D051379:Mice; D008969:Molecular Sequence Data; D005810:Multigene Family / Q000276:immunology*; D021101:Radiation Hybrid Mapping / Q000379:methods; D011961:Receptors, Fc / Q000235:genetics* / Q000378:metabolism / Q000502:physiology; D012689:Sequence Homology, Nucleic Acid
C016512:IgY; D007136:Immunoglobulins; D011961:Receptors, Fc