Identification of viral macrophage inflammatory protein (vMIP)-II as a ligand for GPR5/XCR1

Lymphotactin is unique among chemokines in that it contains only two of fou r conserved cysteines and may possess a structure less constrained than oth er chemokines, The viral chemokine VMIP-II, which presumably has a structur e similar to that of CC chemokines has been shown to inhibit many chemokine receptors, but its activity at GPR5/XCR1 has not been described. Interesti ngly, vMIP-II (but not VMIP-I) was found to be a potent antagonist of lymph otactin activity at GPR5/XCR1, extending the range of chemokine classes tha t this viral protein is known to inhibit to include the C class chemokine. In addition, we have extended previous analyses of GPR5/XCR1 expression and show that this receptor is expressed in leukocyte cells previously shown t o be responsive to lymphotactin. (C) 2000 Academic press.