CX3CR1 is a receptor for the C-X3-C chemokine fractalkine (CX3CL1) which is present on many early leukocyte cells. Fractalkine is a transmembrane protein and chemokine involved in the adhesion and migration of leukocytes. CX3CR1-CX3CL1 signaling exerts distinct functions in different tissue compartments, such as immune response, inflammation, cell adhesion and chemotaxis. CX3CR1 is also a coreceptor for HIV-1, and some variations in this gene lead to increased susceptibility to HIV-1 infection and rapid progression to AIDS. [taken from NCBI Entrez Gene (Gene ID: 1524)].