The enzyme encoded by this gene is an important intermediary in mammalian carbohydrate interconversions. It transfers a glucose moiety from glucose-1-phosphate to MgUTP and forms UDP-glucose and MgPPi. In liver and muscle tissue, UDP-glucose is a direct precursor of glycogen; in lactating mammary gland it is converted to UDP-galactose which is then converted to lactose. The eukaryotic enzyme has no significant sequence similarity to the prokaryotic enzyme. Two transcript variants encoding different isoforms have been found for this gene. [provided by RefSeq, Jul 2008] (from
The crystal structure was determined and shown to form octamers through end-to-end and side-by-side interactions. Mutagenesis studies showed that both dissociation of octamers and mutations of the latch loop can significantly affect the activity.
GYS1 regulation by HIF plays a central role in the hypoxic accumulation of glycogen, and hypoxia also upregulates the expression of UTP:glucose-1-phosphate urydylyltransferase (UGP2) and 1,4-alpha glucan branching enzyme (GBE1)
Kleczkowski et al., Umeå, Sweden. In Plant Cell Physiol, 2009
UGP1 and UGP2, are differentially expressed, with UGP1 being predominant. UGP1 is closely co-regulated with carbohydrate metabolism, late embryogenesis and seed loading, while UGP2 with stress response, fertilized flowers and photosynthetic genes. [UGP1]