Orphan receptor; could be a chemoattractant receptor. Expressed in spleen, lung, heart, liver, kidney, pancreas, thymus, gonads and leukocytes. In most individuals a nonsense mutation transforms the Arg-140 into a premature stop codon. Out of 1217 individuals, 1166 had a stop codon in both alleles, 50 were heterozygous and only one (in the Philippines) had Arg-140 in both alleles. 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.