What Is a Tubulin?

The proteins that tubulin makes up microtubules are called tubulin. Tubulin is a spherical molecule, there are two types: -tubulin and -tubulin. These two tubulins have similar three-dimensional structures and can be tightly combined into two Aggregates, as subunits of microtubule assembly. The alpha subunit is composed of 450 amino acids, and the beta subunit is composed of 455 amino acids. Their molecular weight is about 55 kDa.

Tubulin

tubulin composition

Is a

- and -tubulin polymerization dynamics

At Prosthecobacter

Tubulin eukaryote

The tubulin superfamily contains six tubulins (-, -, -, -, - and -tubulin).

- Tubulin alpha-tubulin

Human alpha-tubulin subtypes include:

· TUBA1A

· TUBA1B

· TUBA1C

· TUBA3C

· TUBA3D

· TUBA3E

· TUBA4A

· TUBA8

- Tubulin -tubulin

All drugs known to bind human tubulin bind to -tubulin. These include paclitaxel, colchicine and vinca alkaloids, each of which has a different binding site on -tubulin.

Class III beta tubulin is a neuron-only representation of microtubule elements and is a neuron-specific neuron epidemic identifier. It binds colchicine more slowly than other isoforms of beta-tubulin.

1-tubulin, sometimes referred to as Class VI -tubulin, differs most at the amino acid sequence level. It is expressed only in human megakaryocytes and platelets, and seems to play an important role in platelet formation. When class VI -tubulins are expressed in mammalian cells, they cause disruption of the microtubule network, the formation of microtubule fragments, and eventually lead to the presence of marginal bands in megakaryocytes and platelets.

Katanin is a protein complex that cuts microtubules on -tubulin subunits and is necessary for rapid microtubule transport in neurons and higher plants.

Human -tubulin subtypes include:

· TUBB

· TUBB1

· TUBB2A

· TUBB2B

· TUBB2C

· TUBB3

· TUBB4

· TUBB4Q

· TUBB6

- Tubulin gamma-tubulin

Gamma-tubulin, another member of the tubulin family, is important in the nucleation and polar orientation of microtubules. It is mainly found in centrosomes and spindle poles because they are the most abundant microtubule nucleation areas. In these organelles, several gamma-tubulin and other protein molecules are found in complexes called gamma-tubulin loop complexes (-TuRCs), which chemically mimic the microtubule's (+) Ends, thereby allowing microtubules to bind. -tubulin is also isolated as a dimer and is part of the -tubulin small complex (TuSC), an intermediate size between the dimer and TuRC. Gamma-tubulin is the best understood mechanism of microtubule nucleation, but some studies have suggested that certain cells may be able to adapt to its deletion, as demonstrated by mutations and RNAi studies that have inhibited its correct expression.

Human gamma-tubulin subtypes include:

TUBG1

TUBG2

Members of the -tubulin loop complex:

TUBGCP2

TUBGCP3

TUBGCP4

TUBGCP5

TUBGCP6

- Tubulin and -tubulin

Delta () and epsilon () tubulins have been found to be localized in the centrosome and may play a role in centromeric structure and function, although they have not been fully studied like the - and -forms.

Human - and -tubulin genes include:

Tubulin

· TUBD1

· -tubulin

· TUBE1

- Tubulin -tubulin

Zeta-tubulin is found in many eukaryotes, but others are missing, including placental mammals. It has been shown to be related to the basal foot structure of centrioles in polycentric epithelial cells.

Tubulin prokaryotes

BtubA / B Tubulin BtubA / B

BtubA / B is found in some bacterial species of the Verrucomicrobial genus Prosthecobacter . Their evolutionary relationship with eukaryotic tubulin is unknown, although they may have been generated from eukaryotic cell lineages through lateral gene transfer.