Ogt

O⁶-alkylguanine DNA alkyltransferase II (O⁶ AGT II) previously known as O⁶ Guanine transferase (ogt) is a bacterial protein that is involved in DNA repair together with Ada ( also known as O⁶ AGT I).

Like AGT I, AGT II is responsible for the removal of alkyl groups from O⁶-alkyl guanine, O⁴-alkyl thymine and alkyl phosphotriester in the sugar-phosphate backbone of DNA. AGT II shows a greater preference for O⁴-alkyl thymine than O⁶-alkyl guanine and alkyl phosphotriester.

Unlike Ada, AGT II is expressed constitutively in cells. Therefore, AGT II will repair alkylated DNA adducts even before Ada is fully induced. AGT II is similar to Ada in its suicide inactivation in that AGT II transfers the alkyl group to a cysteine residue in its own structure, thereby inactivating itself. The human equivalent of AGT II is O⁶-alkylguanine DNA alkyltransferase, a protein that in humans is encoded by the O⁶-methylguanine DNA methyltransferase (MGMT) gene. In humans, O⁶-alkylguanine DNA alkyltransferase preferentially removes alkyl groups from O⁶-alkyl guanine rather than from O⁶–alkyl thymine.

OGT

OGT may be an acronym for:

OGT (gene)

UDP-N-acetylglucosamine—peptide N-acetylglucosaminyltransferase (EC 2.4.1.255), also known as O-linked β-N-acetylglucosamine transferase and O-GlcNAc transferase, OGT is an enzyme that in humans is encoded by the OGT gene.

Function

O-linked N-acetylglucosamine (O-GlcNAc) transferase (OGT) catalyzes the addition of a single N-acetylglucosamine in O-glycosidic linkage to serine or threonine residues of intracellular proteins. Since both phosphorylation and O-GlcNAcylation compete for similar serine or threonine residues, the two processes may compete for sites, or they may alter the substrate specificity of nearby sites by steric or electrostatic effects. The protein contains nine or 14 tetratricopeptide repeats, depending on the splice variant, and a putative bipartite nuclear localization signal. Two alternatively spliced transcript variants encoding distinct isoforms (nucleocytoplasmic and mitochondrial) have been found for this gene. OGT glycosylates many proteins including: Histone H2B,AKT1,PFKL, KMT2E/MLL5,MAPT/TAU,Host cell factor C1, and SIN3A.