TITLE:
Structural and functional consequences of switching carboxy terminal domains in mouse CD200 receptors
AUTHORS:
Ismat Khatri, Ivo Boudakov, Brent Lamptey, Adriana Taseva, Karrie Wong, Anna Podnos, Reginald M. Gorczynski
KEYWORDS:
CD200 Binding; Dap12 Phosphorylation; Domain Switching; Glycosylation; Mabs to mR2
JOURNAL NAME:
Open Journal of Immunology,
Vol.2 No.4,
December
31,
2012
ABSTRACT: CD200:CD200R interactions regulate immune responses. Since CD200Rs show extensive homology in their extracellular region, generating anti-CD200R specific antibodies is a challenge. We report below on the generation of mAbs specific for murine (m)R1/R2 and evidence that mR2 is expressed on the cell surface in the absence of the adaptor protein Dap12. Despite homology between mR1 and mR4, the unexpected reduction in the molecular mass (i.e. 90kDa vs 48kDa) between the two receptors suggested that the TM and cytoplasmic region of mR4 regulated glycosylation. Substitution of the TM and cytoplasmic region of mR1 and mR2 with that of mR4 reduced glycosylation of the chimeric receptors mR1r4 and mR2r4 implying that these regions regulated the glycosylation of mCD200Rs. In activation experiments, phosphorylation of Dap12 following interaction with CD200 occurred on cells expressing mR2V5 but not mR4V5. Similar experiments with the chimeric receptors mR1r2 and mR1r4 also produced phosphorylation of Dap12. Our data suggest that the TM and cytoplasmic region of mCD200Rs dictate their state of glycosylation and provide further evidence that both mCD200R1 and mCD200R2 bind CD200 as ligand with functional consequences for down-stream signaling.