Rate limiting enzyme in the de novo synthesis of guanine nucleotides and therefore is involved in the regulation of cell growth. It may also have a role in the development of malignancy and the growth progression of some tumors.
IMP type I is the main species in normal leukocytes and type II predominates over type I in the tumor.
Purine metabolism; XMP biosynthesis via de novo pathway; XMP from IMP: step 1/1.
Involvement in disease
Defects in IMPDH1 are the cause of retinitis pigmentosa type 10 (RP10) [MIM:180105]. RP leads to degeneration of retinal photoreceptor cells. Patients typically have night vision blindness and loss of midperipheral visual field. As their condition progresses, they lose their far peripheral visual field and eventually central vision as well. RP10 inheritance is autosomal dominant.
Belongs to the IMPDH/GMPR family. Contains 2 CBS domains.