C-C motif chemokine receptor 9,CD199 (CCR9) is a G-protein-coupled 7 TM chemokine receptor for TECK (SCYA25) chemokine. It is expressed strongly in thymus, at lower level in bone marrow and spleen, as well as on a subset of memory T cells specialized for mucosal homing. CD199 appears to confer homing properties to the small intestine on memory T cells. On the other hand it functions as a coreceptor for HIV-1.,GPR-9-6, GPR28