ST3GAL3

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. Mutations in this gene have been associated with autosomal recessive nonsymdromic mental retardation-12 (MRT12). Multiple transcript variants encoding several different isoforms have been found for this gene.

ST3 beta-galactoside alpha-2,3-sialyltransferase 3

Catalyzes the formation of the NeuAc-alpha-2,3-Gal-beta-1,4-GlcNAc-, NeuAc-alpha-2,3-Gal-beta-1,3-GlcNAc- and NeuAc-alpha-2,3-Gal-beta-1,3-GalNAc- sequences found in terminal carbohydrate groups of glycoproteins and glycolipids. The highest activity is toward Gal-beta-1,3-GlcNAc and the lowest toward Gal-beta-1,3-GalNAc.

Biological Process ganglioside biosynthetic process via lactosylceramideIEA:Ensembl
Biological Process keratan sulfate biosynthetic processTAS:Reactome
Biological Process O-glycan processingTAS:Reactome
Biological Process oligosaccharide biosynthetic processTAS:Reactome
Biological Process protein glycosylationManual Assertion Based On ExperimentIBA:GO_Central
Biological Process viral protein processingTAS:Reactome

Golgi apparatus, Golgi stack membrane
Secreted
Membrane-bound form in trans cisternae of Golgi. Secreted into the body fluid.

Intellectual developmental disorder, autosomal recessive 12 (MRT12):
A disorder characterized by significantly below average general intellectual functioning associated with impairments in adaptive behavior and manifested during the developmental period.
Developmental and epileptic encephalopathy 15 (DEE15):
A form of epilepsy that manifests in the neonatal or the early infantile period as severely impaired cognitive and motor development, due to recurrent clinical seizures or prominent interictal epileptiform discharges. Patients develop infantile spasms, mainly of the flexor type, between 3 and 7 months of age, which are accompanied by hypsarrhythmia on EEG. Other features include poor eye contact, hypotonia, primitive reflexes, and irritability. Seizures evolve clinically to Lennox-Gastaut syndrome.

Cytoplasmic: 1-8
Helical: 9-28
Lumenal: 29-375

The soluble form derives from the membrane form by proteolytic processing.