Postsynaptic adhesion molecule that binds to presynaptic neurexins to mediate both excitatory and inhibitory synapse formation . Promotes synapse development by acting as a cell adhesion molecule at the postsynaptic membrane, which associates with both neurexin-alpha and neurexin-beta proteins at the presynaptic membrane . Regulates the balance between excitatory and inhibitory synapses by inhibiting formation of excitatory parallel-fiber synapses and promoting formation of inhibitory synapses in the same neuron (By similarity). May also be involved in ascorbate (vitamin C) uptake via its interaction with SLC23A2/SVCT2 . Complex formation with APBA2 and APP, stabilizes APP metabolism and enhances APBA2-mediated suppression of beta-APP40 secretion, due to the retardation of intracellular APP maturation  (Probable).
Adipose-specific isoform that plays a key role in adaptive thermogenesis. Facilitates the efficient use of stored triglyceride by promoting multilocular morphology of thermogenic adipocytes: acts by inhibiting the activity of CIDEA and CIDEC on lipid droplets, thereby preventing lipid droplet fusion and facilitating lipid utilization. May also participate in adaptive thermogenesis by promoting sympathetic innervation of thermogenic adipose tissue: acts by driving secretion of neurotrophic factor S100B from brown adipocytes, stimulating neurite outgrowth from sympathetic neurons.
Subcellular locations: Postsynaptic cell membrane, Endoplasmic reticulum membrane, Golgi apparatus membrane, Cell projection, Dendrite
Most prominent in the postsynaptic specializations of asymmetric (type I) synapses with both axodendritic and axospinous localization.
Subcellular locations: Lipid droplet, Endoplasmic reticulum membrane
Localizes to endoplasmic reticulum-lipid droplet contact sites through the partitioning of its N-terminal hydrophobic hairpins onto lipid droplets while its C-terminal transmembrane domain remains anchored in the endoplasmic reticulum.
According to , expressed predominantly in the brain and in kidney . Low levels in heart, skeletal muscle, liver, placenta, pancreas and lung . According to , predominant expression in brain, and only marginal in kidney . In brain, present throughout all cortical layers, highest levels in GABAergic neurons (based on morphology and distribution pattern) .
Expression is restricted to adipose tissue, with high expression in multilocular thermogenic adipocytes (brown adipose tissue).