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) and with chondroitin sulfate (By similarity). 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.