| Structural highlights
Disease
GMPPA_HUMAN Triple A syndrome. The disease is caused by variants affecting the gene represented in this entry.
Function
GMPPA_HUMAN Regulatory subunit of the GMPPA-GMPPB mannose-1-phosphate guanylyltransferase complex; reduces the catalytic activity of GMPPB when part of the complex (PubMed:24035193, PubMed:33986552). Mediates allosteric feedback inhibition of GMPPB catalytic activity upon binding GDP-alpha-D-mannose (PubMed:24035193, PubMed:33986552). Together with GMPPB regulates GDP-alpha-D-mannose levels (PubMed:33986552).[1] [2]
Publication Abstract from PubMed
GDP-mannose (GDP-Man) is a key metabolite essential for protein glycosylation and glycophosphatidylinositol anchor synthesis, and aberrant cellular GDP-Man levels have been associated with multiple human diseases. How cells maintain homeostasis of GDP-Man is unknown. Here, we report the cryo-EM structures of human GMPPA-GMPPB complex, the protein machinery responsible for GDP-Man synthesis, in complex with GDP-Man or GTP. Unexpectedly, we find that the catalytically inactive subunit GMPPA displays a much higher affinity to GDP-Man than the active subunit GMPPB and, subsequently, inhibits the catalytic activity of GMPPB through a unique C-terminal loop of GMPPA. Importantly, disruption of the interactions between GMPPA and GMPPB or the binding of GDP-Man to GMPPA in zebrafish leads to abnormal brain development and muscle abnormality, analogous to phenotypes observed in individuals carrying GMPPA or GMPPB mutations. We conclude that GMPPA acts as a cellular sensor to maintain mannose homeostasis through allosterically regulating GMPPB.
Cryo-EM structures of human GMPPA-GMPPB complex reveal how cells maintain GDP-mannose homeostasis.,Zheng L, Liu Z, Wang Y, Yang F, Wang J, Huang W, Qin J, Tian M, Cai X, Liu X, Mo X, Gao N, Jia D Nat Struct Mol Biol. 2021 May;28(5):1-12. doi: 10.1038/s41594-021-00591-9. Epub , 2021 May 13. PMID:33986552[3]
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
References
- ↑ Koehler K, Malik M, Mahmood S, Gießelmann S, Beetz C, Hennings JC, Huebner AK, Grahn A, Reunert J, Nürnberg G, Thiele H, Altmüller J, Nürnberg P, Mumtaz R, Babovic-Vuksanovic D, Basel-Vanagaite L, Borck G, Brämswig J, Mühlenberg R, Sarda P, Sikiric A, Anyane-Yeboa K, Zeharia A, Ahmad A, Coubes C, Wada Y, Marquardt T, Vanderschaeghe D, Van Schaftingen E, Kurth I, Huebner A, Hübner CA. Mutations in GMPPA cause a glycosylation disorder characterized by intellectual disability and autonomic dysfunction. Am J Hum Genet. 2013 Oct 3;93(4):727-34. PMID:24035193 doi:10.1016/j.ajhg.2013.08.002
- ↑ Zheng L, Liu Z, Wang Y, Yang F, Wang J, Huang W, Qin J, Tian M, Cai X, Liu X, Mo X, Gao N, Jia D. Cryo-EM structures of human GMPPA-GMPPB complex reveal how cells maintain GDP-mannose homeostasis. Nat Struct Mol Biol. 2021 May;28(5):1-12. PMID:33986552 doi:10.1038/s41594-021-00591-9
- ↑ Zheng L, Liu Z, Wang Y, Yang F, Wang J, Huang W, Qin J, Tian M, Cai X, Liu X, Mo X, Gao N, Jia D. Cryo-EM structures of human GMPPA-GMPPB complex reveal how cells maintain GDP-mannose homeostasis. Nat Struct Mol Biol. 2021 May;28(5):1-12. PMID:33986552 doi:10.1038/s41594-021-00591-9
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