GPR105 belongs to the family of G protein-coupled receptors, which contains several receptor subtypes with different pharmacological selectivity for various adenosine and uridine nucleotides. GPR105 is a P2Y purinergic receptor for UDP-glucose and other UDP-sugars coupled to G proteins. It has been implicated in extending the known immune system functions of P2Y receptors by participating in the regulation of the stem cell compartment. It may also play a role in neuroimmune function.