Background：The protein encoded by this gene acts as a homotetramer to regulate cell growth. The encoded protein is an enzyme that catalyzes the synthesis of xanthine monophosphate （XMP） from inosine-5'-monophosphate （IMP）. This is the rate-limiting step in the de novo synthesis of guanine nucleotides. Defects in this gene are a cause of retinitis pigmentosa type 10 （RP10）. Several transcript variants encoding different isoforms have been found for this gene.
