Tubulin
From Wikipedia, the free encyclopedia
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tubulin, alpha 1 (testis specific)
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| Identifiers | |
| Symbol(s) | TUBA1 |
| Entrez | 7277 |
| OMIM | 191110 |
| RefSeq | NM_006000 |
| UniProt | P68366 |
| Other data | |
| Locus | Chr. 2 q36.1 |
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tubulin, alpha 2
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| Identifiers | |
| Symbol(s) | TUBA2 |
| Entrez | 7278 |
| OMIM | 602528 |
| RefSeq | NM_006001 |
| UniProt | Q13748 |
| Other data | |
| Locus | Chr. 13 q11 |
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tubulin, beta
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| Identifiers | |
| Symbol(s) | TUBB |
| Entrez | 203068 |
| OMIM | 191130 |
| RefSeq | NM_178014 |
| UniProt | P07437 |
| Other data | |
| Locus | Chr. 6 p21.33 |
A Tubulin is one of several members of a small family of globular proteins. The most common members of the tubulin family are α-tubulin and β-tubulin, the proteins which makes up microtubules. Each has a molecular weight of approximately 55 kiloDaltons. Microtubules are assembled from dimers of α- and β-tubulin. γ-tubulin, another member of the tubulin family, is important in the nucleation and polar orientation of microtubules.
To form microtubules, the dimers of α- and β-tubulin bind to GTP and assemble onto the (+) ends of microtubules while in the GTP-bound state. After being incorporated into the microtubule, the bound molecule of GTP will hydrolize into GDP. Although both subunits bind GTP, only the β-subunit has GTPase activity; that is, β-tubulin can hydrolize GTP to GDP whereas α-tubulin cannot. Whether the β-tubulin member of the tubulin dimer is bound to GTP or GDP influences the stability of the dimer in the microtubule. Dimers bound to GTP tend to assemble into microtubules, while dimers bound to GDP tend to fall apart; thus, this GTP cycle is essential for the dynamic instability of the microtubule.
Tubulin was long thought to be specific to eukaryotes. Recently, however, the prokaryotic cell division protein FtsZ was shown to be evolutionarily related to tubulin.
Delta (δ) and epsilon (ε) tubulin have been found to localize at centrioles and may play a role in forming the mitotic spindle during mitosis, though neither is as well-studied as the α- and β- forms
[edit] Pharmacology
Tubulins are targets for anticancer drugs like Taxol® and the "Vinca alkaloid" drugs such as vinblastine and vincristine. The anti-gout agent colchicine binds to tubulin and inhibits microtubule formation, arresting neutrophil motility and decreasing inflammation.
[edit] See also
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Proteins of the cytoskeleton
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| Microfilaments | Actins | Myosins | Actin-binding proteins |
| Intermediate filaments | IFAPs | Keratins | Lamins | Neurofilaments | Type III IF proteins |
| Microtubules | Dyneins | Kinesins | MAPs | Tubulins |
| Prokaryotic cytoskeleton | Crescentin | FtsZ | MreB |
| Other | Major Sperm Proteins |
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