sialyltransferase 4B; ST3GAL2; CMP-N-acetylneuraminate-beta-galactosamide-alpha-2,3-sialyltransferase; beta-galactoside alpha-2,3-sialyltransferase; gal-beta-1,3-GalNAc-alpha-2,3-sialyltransferase (SIAT4B)

Function

• may be responsible for synthesis of the sequence neuAc-alpha-2,3-gal-beta-1,3-galNAc- found in terminal carbohydrate groups of certain glycoproteins, oligosaccharides & glycolipids
• SIAT4A & SIAT4B sialylate the same acceptor substrates but exhibit different Km values
• protein modification; protein glycosylation
• the soluble form derives from the membrane form by proteolytic processing (putative)

CMP-N-acetylneuraminate +
beta-D-galactosyl-1,3-N-acetyl-alpha-D-galactosaminyl-R
                 <-->
CMP + alpha-N-acetylneuraminyl-2,3-beta-D-galactosyl-1,3-N- acetyl-alpha-D-galactosaminyl-R

Structure

belongs to the glycosyltransferase 29 family

Compartment

• Golgi, Golgi stack membrane
• secreted
• membrane-bound form in trans cisternae of Golgi
• secreted into the body fluid (putative)

Expression

• expressed in skeletal muscle & heart >> brain, placenta, liver & pancreas
• scarcely detectable in lung & kidney

More general terms

• sialyltransferase
• membrane protein
• glycoprotein

Database

• Kegg: http://www.genome.jp/dbget-bin/www_bget?hsa:6483
• OMIM: https://mirror.omim.org/entry/607188
• UniProt: http://www.uniprot.org/uniprot/Q16842.html
• Entrez gene: http://www.ncbi.nlm.nih.gov/sites/entrez?db=gene&cmd=Retrieve&dopt=Graphics&list_uids=6483