ST3 beta-galactoside alpha-2,3-sialyltransferase 3, also known as ST3GAL3, is a protein which in humans is encoded by the ST3GAL3 gene.[5][6]
The protein encoded by this gene is a type II membrane protein that catalyzes the transfer of sialic acid from CMP-sialic acid to galactose-containing substrates. The encoded protein is normally found in the Golgi apparatus but can be proteolytically processed to a soluble form. This protein is a member of glycosyltransferase family 29. Multiple transcript variants encoding several different isoforms have been found for this gene.[6]
Mutations in the ST3GAL3 gene was recently shown to be the cause of autosomal recessive mental retardation 12. Since the mutations disrupt a glycosylation pathway, this disorder may be considered a congenital disorder of glycosylation.