Receptor potentially involved in both adhesion and signaling processes early after leukocyte activation. Plays an essential role in leukocyte migration. Forms a heterodimer, consisting of a large extracellular region (alpha subunit) non-covalently linked to a seven-transmembrane moiety (beta subunit). Interacts with complement decay-accelerating factor (DAF). The largest isoform (isoform 1) do not interact with DAF. Interacts also with chondroitin sulfate (By similarity). Although predominantly expressed by cells of the immune system, expressed ubiquitously with particularly high levels of expression in the lung and the thymus gland. In the spleen, expression is detected on most myeloid cells and variable portions of T-cells, B-cells and NK cells. In the bone marrow, expressed in nearly all myeloid cells, whereas little if any expression is found on erythroid cells. Up-regulated during lymphocyte activation. The first two EGF domains mediate the interaction with DAF. A third tandemly arranged EGF domain is necessary for the structural integrity of the binding region (By similarity). Binding to chondroitin sulfate is mediated by the fourth EGF domain. Proteolytically cleaved into 2 subunits, an extracellular alpha subunit and a seven-transmembrane subunit. Belongs to the G-protein coupled receptor 2 family. LN-TM7 subfamily.