APRG1 is a 170 amino acid single-pass membrane protein that exists as 3 alternatively spliced isoforms. APRG1 isoform 1 is highly expressed in placenta and pancreas, while isoform 2 is mainly expressed in kidney. The gene encoding APRG1 maps to human chromosome 3, which houses over 1,100 genes, including a chemokine receptor (CKR) gene cluster and a variety of human cancer-related gene loci. Key tumor suppressing genes on chromosome 3 include those that encode the apoptosis mediator RASSF1, the cell migration regulator HYAL1 and the angiogenesis suppressor SEMA3B. Marfan syndrome, porphyria, von Hippel-Lindau syndrome, osteogenesis imperfecta and Charcot-Marie-Tooth disease are a few of the numerous genetic diseases associated with chromosome 3.