Polypeptide N-acetylgalactosaminyltransferase 1 is an
enzyme that in
humans is encoded by the ''GALNT1''
gene.
This gene encodes a member of the UDP-N-acetyl-alpha-D-
galactosamine:
polypeptide
Peptides (, ) are short chains of amino acids linked by peptide bonds. Long chains of amino acids are called proteins. Chains of fewer than twenty amino acids are called oligopeptides, and include dipeptides, tripeptides, and tetrapeptides.
A p ...
N-
acetylgalactosaminyltransferase (GalNAc-T) family of enzymes. GalNAc-Ts initiate
mucin-type O-linked
glycosylation
Glycosylation is the reaction in which a carbohydrate (or ' glycan'), i.e. a glycosyl donor, is attached to a hydroxyl or other functional group of another molecule (a glycosyl acceptor) in order to form a glycoconjugate. In biology (but not al ...
in the
Golgi apparatus by
catalyzing the transfer of GalNAc to
serine
Serine (symbol Ser or S) is an α-amino acid that is used in the biosynthesis of proteins. It contains an α-amino group (which is in the protonated − form under biological conditions), a carboxyl group (which is in the deprotonated − form un ...
and
threonine
Threonine (symbol Thr or T) is an amino acid that is used in the biosynthesis of proteins. It contains an α-amino group (which is in the protonated −NH form under biological conditions), a carboxyl group (which is in the deprotonated −COOâ ...
residues on target
proteins. They are characterized by an
N-terminal
The N-terminus (also known as the amino-terminus, NH2-terminus, N-terminal end or amine-terminus) is the start of a protein or polypeptide, referring to the free amine group (-NH2) located at the end of a polypeptide. Within a peptide, the ami ...
transmembrane domain, a stem region, a lumenal catalytic domain containing a GT1 motif and Gal/GalNAc
transferase motif, and a C-terminal
ricin
Ricin ( ) is a lectin (a carbohydrate-binding protein) and a highly potent toxin produced in the seeds of the castor oil plant, ''Ricinus communis''. The median lethal dose (LD50) of ricin for mice is around 22 micrograms per kilogram of body ...
/
lectin
Lectins are carbohydrate-binding proteins that are highly specific for sugar groups that are part of other molecules, so cause agglutination of particular cells or precipitation of glycoconjugates and polysaccharides. Lectins have a role in rec ...
-like domain. GalNAc-Ts have different, but overlapping,
substrate specificities and patterns of expression. Transcript variants derived from this gene that utilize alternative polyA signals have been described in the literature.
References
Further reading
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
{{gene-18-stub