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Domain

The highly acidic C-terminal region may bind cations such as calcium.

The MREI motif is common among all beta-tubulin isoforms and may be critical for tubulin autoregulation.

Function

Tubulin is the major constituent of microtubules, a cylinder consisting of laterally associated linear protofilaments composed of alpha- and beta-tubulin heterodimers. Microtubules grow by the addition of GTP-tubulin dimers to the microtubule end, where a stabilizing cap forms. Below the cap, tubulin dimers are in GDP-bound state, owing to GTPase activity of alpha-tubulin. TUBB3 plays a critical role in proper axon guidance and maintenance. Binding of NTN1/Netrin-1 to its receptor UNC5C might cause dissociation of UNC5C from polymerized TUBB3 in microtubules and thereby lead to increased microtubule dynamics and axon repulsion. Plays a role in dorsal root ganglion axon projection towards the spinal cord.

Post-translational modifications

Some glutamate residues at the C-terminus are polyglycylated, resulting in polyglycine chains on the gamma-carboxyl group. Glycylation is mainly limited to tubulin incorporated into axonemes (cilia and flagella) whereas glutamylation is prevalent in neuronal cells, centrioles, axonemes, and the mitotic spindle. Both modifications can coexist on the same protein on adjacent residues, and lowering polyglycylation levels increases polyglutamylation, and reciprocally. Cilia and flagella glycylation is required for their stability and maintenance. Flagella glycylation controls sperm motility.

Some glutamate residues at the C-terminus are polyglutamylated, resulting in polyglutamate chains on the gamma-carboxyl group (By similarity). Polyglutamylation plays a key role in microtubule severing by spastin (SPAST). SPAST preferentially recognizes and acts on microtubules decorated with short polyglutamate tails: severing activity by SPAST increases as the number of glutamates per tubulin rises from one to eight, but decreases beyond this glutamylation threshold (By similarity). Glutamylation is also involved in cilia motility (By similarity).

Phosphorylated on Ser-172 by CDK1 during the cell cycle, from metaphase to telophase, but not in interphase. This phosphorylation inhibits tubulin incorporation into microtubules.

Sequence similarities

Belongs to the tubulin family.

Cellular localization

  • Cytoplasm
  • Cytoskeleton
  • Cell projection
  • Growth cone
  • Cell projection
  • Lamellipodium
  • Cell projection
  • Filopodium

Alternative names

Tubulin beta-3 chain, Neuron-specific class III beta-tubulin, Tubb3

Target type

Proteins

Primary research area

Neuroscience

Other research areas

  • Immunology & Infectious Disease

Molecular weight

50419Da