The orthologue of human IGPR-1 is found only in eukaryotes, including primates, the guinea pig, canines, felines, dolphins, bovines, the llama, bats, the common shrew, and horses. Of interest, the IGPR-1 gene is absent in mouse and rat genomes. The immunoglobulin domain of IGPR-1 was predicted to be Ig V (variable) fold and was found to be highly similar to the Ig domain of myelin-associated glycoprotein.