Receptor CCR9 binds CCL25 ligand

CCR9 (previously called orphan receptor GPR 9-6) is highly expressed in the thymus on both mature and immature T-cells. It is also abundant in T-cells of the intestine but is lowly expressed in lymph nodes and the spleen. Alternative splicing produces two receptors, called CCR9A and CCR9B, CCR9A containing 12 additional amino acids at its N terminus as compared with CCR9B (Yu CR et al, 2000). The A and B forms of the receptor were expressed at a ratio of approximately 10:1. CCR9 has a specific ligand in CCL25 (Thymus-expressed chemokine, TECK) (Zaballos A et al, 1999) and transduces the signal by intracellular calcium mobilization.

CCR9（此前称为孤儿受体GPR 9-6）在胸腺中高表达于成熟及未成熟T细胞。此外，该受体在肠道T细胞中含量丰富，但在淋巴结和脾脏中表达水平较低。通过选择性剪接，CCR9可产生两种受体，即CCR9A和CCR9B，其中CCR9A相较于CCR9B在其N端额外含有12个氨基酸（Yu CR et al, 2000）。两种受体的表达比例为约10:1。CCR9具有特异的配体CCL25（胸腺表达趋化因子，TECK）(Zaballos A et al, 1999)，并通过细胞内钙离子的动员传递信号。