Orphan receptor; could be a chemoattractant receptor. In some individuals a nonsense mutation transforms either Ser-39 or Arg-140 into a premature stop codon. GPR33 has undergone independent pseudogenization in human, chimpanzee, orangutan 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.