Mannose-1-phosphate guanyltransferase beta (GMPPB)

Mannose-1-phosphate guanyltransferase beta (GMPPB) is a cytoplasmic enzyme that catalyzes the conversion of mannose-1-phosphate and GTP to GDP-mannose, a key sugar nucleotide required for biosynthesis of glycoproteins and glycolipids through various glycosylation pathways, including O-mannosylation, N-glycosylation, and C-mannosylation[1][2][3]. GDP-mannose produced by GMPPB is an essential substrate for mannosyltransferases in the endoplasmic reticulum, supporting the maturation of proteins such as alpha-dystroglycan (α-DG), which anchors muscle and brain cells to the extracellular matrix[1]. Pathogenic mutations in the *GMPPB* gene result in a spectrum of neuromuscular disorders, mainly forms of muscular dystrophy and congenital myasthenic syndromes, by impairing glycosylation of α-dystroglycan and disturbing cellular differentiation and function[1][2]. GMPPB is indispensable for early embryogenesis—complete loss-of-function leads to embryonic lethality in mice—highlighting its crucial, non-redundant biological role[2]. To date, there are no drugs specifically targeting GMPPB, but glycosylation defects associated with GMPPB mutations may be explored in rare disease diagnostics and research[1][2].

Other names

GDP-mannose pyrophosphorylase BGTP-mannose-1-phosphate guanylyltransferase betaKIAA1851LGMDR19MDDGA14MDDGB14MDDGC14mannose-1-phosphate guanylyltransferase catalytic subunit betamannose-1-phosphate guanyltransferase beta

Not applicable for direct drug targeting (no approved drugs act directly on GMPPB as of current knowledge)