Sandbox Reserved 381: Difference between revisions
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== OGT Features of Interest == | == OGT Features of Interest == | ||
OGT is the only known member to glycosylate polypeptides and it contains a long uncharacterized intervening sequence (~120 amino acids) in the middle of the catalytic region. Studies suggest that OGT contains a phosphatidylinositol (3,4,5)-trisphosphate (PIP3)binding domain. The most unusual feature of OGT is the intervening domain between the catalytic lobes, which is only found in metazoans. This polypeptide adopts a topologically novel fold with a seven-stranded <scene name='Sandbox_Reserved_381/Ogt_structure/1'>beta</scene> | OGT is the only known member to glycosylate polypeptides and it contains a long uncharacterized intervening sequence (~120 amino acids) in the middle of the catalytic region. Studies suggest that OGT contains a phosphatidylinositol (3,4,5)-trisphosphate (PIP3)binding domain. The most unusual feature of OGT is the intervening domain between the catalytic lobes, which is only found in metazoans. This polypeptide adopts a topologically novel fold with a seven-stranded <scene name='Sandbox_Reserved_381/Ogt_structure/1'>beta sheet</scene> core stabilized by flanking alpha helices. There are two long <scene name='Sandbox_Reserved_381/Unstructured_loops/1'>unstructured loops</scene> for which electron density is missing.<ref> PMID:18288188</ref> | ||
== OGT Structure == | == OGT Structure == | ||
OGT is comprised of two distinct regions: a multidomain catalytic region, which has no available structure and an N-terminal region consisting of a seris of tetratricopeptide repeat(TPR) units.<ref>PMID:9083067</ref> The N terminus of OGT is unusual, consisting of 2.5-13.5 tetratricopeptide repeats (TPRs) depending on alternative splicing.<ref>Kreppel L, Hart G. Regulation of a cytosolic and nuclear O-GlcNAc transferase. Role of the tetratricopeptide repeats. J Biol Chem. 1999;274:32015-32022</ref> The N-terminal domain of tetratricopeptide (TPR) mediates the recognition of a broad range of target proteins. Components of the nuclear pore complex are major OGT targets, as OGT depletion by RNA interference (RNAi) results in the loss of GlcNAc modification at the nuclear envelope. | OGT is comprised of two distinct regions: a multidomain catalytic region, which has no available structure and an N-terminal region consisting of a seris of tetratricopeptide repeat(TPR) units.<ref>PMID:9083067</ref> The N terminus of OGT is unusual, consisting of 2.5-13.5 tetratricopeptide repeats (TPRs) depending on alternative splicing.<ref>Kreppel L, Hart G. Regulation of a cytosolic and nuclear O-GlcNAc transferase. Role of the tetratricopeptide repeats. J Biol Chem. 1999;274:32015-32022</ref> The N-terminal domain of tetratricopeptide (TPR) mediates the recognition of a broad range of target proteins. Components of the nuclear pore complex are major OGT targets, as OGT depletion by RNA interference (RNAi) results in the loss of GlcNAc modification at the nuclear envelope. | ||
== N Terminus == | |||
==N Terminus==<StructureSection load='1W3B' size='250' side='left' caption='Superhilical TPR domain of OGT, structural similarities to importin alpha. (PDB entry [[1W3B]])' scene=''>The crystal structure of the homodimeric TPR domain of human OGT, which contains 11.5 TPR repeats gives insight into the mechanism of target recognition. The repeats form an elongated superhilix. The concave surface of the superhelix is lined by absolutely conserved asparagines, in a manner reminiscent of the peptide-binding site of importin alpha. Based on this structural similarity, it is proposed that OGT uses an analogous molecular mechanism to recognize its targets.<ref>PMID:15361863</ref> </StructureSection> | <StructureSection load='1W3B' size='250' side='left' caption='Superhilical TPR domain of OGT, structural similarities to importin alpha. (PDB entry [[1W3B]])' scene=''>The crystal structure of the homodimeric TPR domain of human OGT, which contains 11.5 TPR repeats gives insight into the mechanism of target recognition. The repeats form an elongated superhilix. The concave surface of the superhelix is lined by absolutely conserved asparagines, in a manner reminiscent of the peptide-binding site of importin alpha. Based on this structural similarity, it is proposed that OGT uses an analogous molecular mechanism to recognize its targets.<ref>PMID:15361863</ref> </StructureSection> | ||
== OGT Mediated Disease == | == OGT Mediated Disease == | ||
