Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:2.3.1.108 (TAT)
 2,389 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A tight association between Chlamydomonas alpha-tubulin acetyltransferase (TAT) and flagellar axonemes, and the cytoplasmic localization of both tubulin deacetylase (TDA) and an inhibitor of tubulin acetylation have been demonstrated by the use of calf brain tubulin as substrate for these enzymes. A major axonemal TAT of 130 kD has been solubilized by high salt treatment, purified, and characterized. Using the Chlamydomonas TAT with brain tubulin as substrate, we have studied the effects of acetylation on the assembly and disassembly of microtubules in vitro. We also determined the relative rates of acetylation of tubulin dimers and polymers. The acetylation does not significantly affect the temperature-dependent polymerization or depolymerization of tubulin in vitro. Furthermore, polymerization of tubulin is not a prerequisite for the acetylation, although the polymer is a better substrate for TAT than the dimer. The acetylation is sensitive to calcium ions which completely inhibit the acetylation of both dimers and polymers of tubulin. Acetylation of the dimer is not inhibited by colchicine; the effect of colchicine on acetylation of the polymer can be explained by its depolymerizing effect on the polymer.
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PMID:The acetylation of alpha-tubulin and its relationship to the assembly and disassembly of microtubules. 373 80

We have previously shown that the alpha-tubulin of Chlamydomonas flagella is synthesized as a precursor which is modified by acetylation in the flagellum during flagellar assembly. In this report, we show the presence of an alpha-tubulin acetylase activity in isolated Chlamydomonas flagella that is highly specific for alpha-tubulin of both mammalian brain and Chlamydomonas.
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PMID:Alpha-tubulin acetylase activity in isolated Chlamydomonas flagella. 406 51

An assay for alpha-tubulin acetyltransferase (TAT) activity based on affinity isolation of labeled acetylated alpha-tubulin was developed for use with crude subcellular fractions. Microtubules were polymerized and immobilized on an anti-alpha-tubulin-agarose and then incubated with the subcellular fraction and [3H]acetyl-coenzyme A (CoA). The labeled product was eluted from the antibody-agarose and the tritiated acetate incorporation determined. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis and immunoblot of the eluate verified the presence of acetyl-alpha-tubulin. Analysis of bovine retinal fractions showed the highest specific activity of tubulin acetyltransferase activity in the 27,000g pellet fraction (P2) of retinal homogenates. This transferase activity was proportional to the concentration of microtubule protein immobilized under polymerizing conditions and had an apparent Km of 3 microM for acetyl-CoA. The activity was solubilized from the P2 pellet by a high ionic strength buffer. The properties of the retinal TAT determined by this assay are very similar to those reported for a more purified enzyme preparation from Chlamydomonas flagella using the conventional trichloroacetic acid precipitation assay and support the use of this method for samples in which high backgrounds prohibit use of the conventional assay.
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PMID:Assay of tubulin acetyltransferase activity in subcellular tissue fractions. 813 64

In most eukaryotic cells, subsets of microtubules are adapted for specific functions by post-translational modifications (PTMs) of tubulin subunits. Acetylation of the epsilon-amino group of K40 on alpha-tubulin is a conserved PTM on the luminal side of microtubules that was discovered in the flagella of Chlamydomonas reinhardtii. Studies on the significance of microtubule acetylation have been limited by the undefined status of the alpha-tubulin acetyltransferase. Here we show that MEC-17, a protein related to the Gcn5 histone acetyltransferases and required for the function of touch receptor neurons in Caenorhabditis elegans, acts as a K40-specific acetyltransferase for alpha-tubulin. In vitro, MEC-17 exclusively acetylates K40 of alpha-tubulin. Disruption of the Tetrahymena MEC-17 gene phenocopies the K40R alpha-tubulin mutation and makes microtubules more labile. Depletion of MEC-17 in zebrafish produces phenotypes consistent with neuromuscular defects. In C. elegans, MEC-17 and its paralogue W06B11.1 are redundantly required for acetylation of MEC-12 alpha-tubulin, and contribute to the function of touch receptor neurons partly via MEC-12 acetylation and partly via another function, possibly by acetylating another protein. In summary, we identify MEC-17 as an enzyme that acetylates the K40 residue of alpha-tubulin, the only PTM known to occur on the luminal surface of microtubules.
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PMID:MEC-17 is an alpha-tubulin acetyltransferase. 2082 95