Plays a role in cell-cell adhesion and neuron guidance via its interactions with FLRT2 and FLRT3 that are expressed at the surface of adjacent cells (PubMed:22405201, PubMed:25728924, PubMed:26235031). Plays a role in the development of glutamatergic synapses in the cortex (PubMed:22405201, PubMed:24739570). Important in determining the connectivity rates between the principal neurons in the cortex (PubMed:24739570). Interacts (via olfactomedin-like domain) with FLRT3 (via extracellular domain); the interaction is direct(PubMed:22405201, PubMed:24739570, PubMed:26235031). Identified in a complex with FLRT3 and UNC5B; does not interact with UNC5B by itself. Identified in a complex with FLRT3 and UNC5D; does not interact with UNC5D by itself (By similarity). Interacts (via olfactomedin-like domain) with FLRT1 (via extracellular domain) (PubMed:22405201). Interacts (via olfactomedin-like domain) with FLRT2 (via extracellular domain) (PubMed:22405201, PubMed:25728924). Interacts (via extracellular domain) with TENM1 (PubMed:24739570). Interacts (via extracellular domain) with TENM3 (PubMed:22405201). The Olfactomedin-like domain is required for the synapse-promoting function and the interaction with FLRT3. The Olfactomedin-like and the SUEL-type lectin domains are required for the interaction with TENM1. Proteolytically cleaved into 2 subunits, an extracellular subunit and a seven-transmembrane subunit. O-glycosylated (major) and N-glycosylated. Mutant mice are viable and present no obvious physical phenotype. Compared to wild-type, mutants are hyperactive, and their dorsal striatum contains higher levels of the neurotransmitters dopamine and serotonin. Cocaine treatment causes a higher increase in locomotor activity than in wild-type. Belongs to the G-protein coupled receptor 2 family. LN-TM7 subfamily.