Orphan receptor; could be a chemoattractant receptor. In Rattus norvegicus, Gpr33 is disrupted by a 14 bp deletion. GPR33 has undergone independent pseudogenization in human, chimpanzee, orangutan, siamang and rat. This selective inactivation may be due to its interaction with a putative pathogen that could use GPR33 as a receptor for cell invasion. Belongs to the G-protein coupled receptor 1 family.