May regulate the number of excitatory synapses that are formed on hippocampus neurons. Has no effect on inhibitory synapses. Plays a role in glucose homeostasis. Via AMPK signaling pathway, stimulates glucose uptake in adipocytes, myotubes and hepatocytes and enhances insulin-stimulated glucose uptake. In a hepatoma cell line, reduces the expression of gluconeogenic enzymes G6PC1 and PCK1 and hence decreases de novo glucose production. Forms homooligomers. Interacts with ADGRB3 (PubMed:21262840). Forms heterooligomers with C1QL2 and C1QL4, when proteins are coexpressed; this interaction does not occur after secretion. Highly expressed in brain and white adipose tissue. In gonadal fat pad, expressed at lower levels in adipocytes than in the stromal vascular fraction (VSP), which contains preadipocytes, fibroblasts, endothelial cells and occasional immune cells. Expression exhibits sexually dimorphism, with higher levels in females than in males (at protein level). Tends to be up-regulated in adipose tissue from obese males, but not females. Expressed in glial cells. In adipocytes, up-regulated by rosiglitazone, an insulin-sensitizing drug.