Tubulin
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| tubulin, alpha 1 (testis specific)
| |
| Identifiers | |
| Symbol | TUBA1 |
| Entrez | 7277 |
| HUGO | 12407 |
| OMIM | 191110 |
| RefSeq | NM_006000 |
| UniProt | P68366 |
| Other data | |
| Locus | Chr. 2 q36.1 |
| tubulin, alpha 2
| |
| Identifiers | |
| Symbol | TUBA2 |
| Entrez | 7278 |
| HUGO | 12408 |
| OMIM | 602528 |
| RefSeq | NM_006001 |
| UniProt | Q13748 |
| Other data | |
| Locus | Chr. 13 q11 |
| tubulin, beta
| |
| Identifiers | |
| Symbol | TUBB |
| Entrez | 203068 |
| HUGO | 20778 |
| 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. These subunits are slightly acidic with an isoelectric point between 5.2 and 5.8.
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.
α-tubulin and β-tubulin
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 hydrolyse into GDP.
Although both subunits bind GTP, only the β-subunit has GTPase activity; that is, β-tubulin can hydrolyse 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.
Class III β-tubulin is a microtubule element expressed exclusively in neurons, and is a popular identifier specific for neurons in nervous tissue.
Katanin is a protein complex that severs β-tubulin, and is necessary for rapid microtubule transport in neurons and in higher plants.
Human α- and β-tubulin subtypes include:
- α-tubulin
- β-tubulin
γ-tubulin
γ-tubulin, another member of the tubulin family, is important in the nucleation and polar orientation of microtubules.
δ and ε 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
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.
See also
External links
Proteins of the cytoskeleton | |
|---|---|
| Microfilaments | Actins - Actin-binding proteins - Actinin - Arp2/3 complex - Cofilin - Destrin - Gelsolin - Myosins - Profilin - Tropomodulin - Troponin (T, C, I) - Tropomyosin - Wiskott-Aldrich syndrome protein |
| Intermediate filaments | type 1 and 2 (Cytokeratin, type I, type II) - type 3 (Desmin, GFAP, Peripherin, Vimentin) - type 4 (Internexin, Nestin, Neurofilament, Synemin, Syncoilin) - type 5 (Lamin A, B) |
| Microtubules | Dyneins - Kinesins - MAPs (Tau protein, Dynamin) - Tubulins - Stathmin - Tektin |
| Catenins | Alpha catenin - Beta catenin - Plakoglobin (gamma catenin) - Delta catenin |
| Nonhuman | Major sperm proteins - Prokaryotic cytoskeleton (Crescentin, FtsZ, MreB) |
| Other | APC - Dystrophin (Dystroglycan) - plakin (Desmoplakin, Plectin) - Spectrin - Talin - Utrophin - Vinculin |
Acid anhydride hydrolases: GTPases/G proteins (EC 3.6.5) | |
|---|---|
| 3.6.5.1: Heterotrimeric G protein | Gαs - Gαi (GNAI1, GNAI2, GNAI3) - Gαq/11 (GNAQ, GNA11) - Gα12/13 (GNA12, GNA13) - Transducin (GNAT1, GNAT2) |
| 3.6.5.2: Small GTPase > Ras superfamily | Ras - Rab (Rab27) - Arf (Arf6) - Ran - Rheb - Rho family (RhoA, RhoB, CDC42, Rac1) - Rap |
| 3.6.5.3: Elongation factor | Prokaryotic - Eukaryotic |
| 3.6.5.5-6: Other | Dynamin (is a GTPase, is not a G protein) - Tubulin |
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Acknowledgement and Attribution Regarding Sources of Content
Some of the initial content on this page may be incorporated in part from copyleft sources in the public domain including wikis such as Wikipedia and AskDrWiki. Drug information for patients came from the The National Library of Medicine. Infectious disease information may have come from the Centers for Disease Control (CDC). Differential Diagnoses are drawn from clinicians as well as an amalgamation of 3 sources: 1.The Disease Database; 2. Kahan, Scott, Smith, Ellen G. In A Page: Signs and Symptoms. Malden, Massachusetts: Blackwell Publishing, 2004:3; 3. Sailer, Christian, Wasner, Susanne. Differential Diagnosis Pocket. Hermosa Beach, CA: Borm Bruckmeir Publishing LLC, 2002:7 .
