TUBA8

TUBA8 is a member of the alpha tubulin protein family. Alpha tubulins are one of two core protein families (alpha and beta tubulins) that heterodimerize and assemble to form microtubules. Mutations in TUBA8 are associated with polymicrogyria and optic nerve hypoplasia.

Tubulin Alpha 8

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.

Biological Process microtubule cytoskeleton organization Source:GO_Central1 Publication
Biological Process mitotic cell cycle Source:GO_Central1 Publication

Cytoplasm, cytoskeleton

Cortical dysplasia, complex, with other brain malformations 8 (CDCBM8):
A disease characterized by extensive polymicrogyria, optic nerve hypoplasia, severe developmental delay, hypotonia, seizures, a dysplastic or absent corpus callosum and colpocephaly. Polymicrogyria is a malformation of the cortex in which the brain surface is irregular and characterized by an excessive number of small gyri with abnormal lamination. Polymicrogyria is a heterogeneous disorder, considered to be the result of postmigratory abnormal cortical organization.

Some glutamate residues at the C-terminus are polyglutamylated, resulting in polyglutamate chains on the gamma-carboxyl group (PubMed:26875866).
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 (PubMed:26875866).
Glutamylation is also involved in cilia motility (By similarity).
Some glutamate residues at the C-terminus are monoglycylated but not polyglycylated due to the absence of functional TTLL10 in human. Monoglycylation is mainly limited to tubulin incorporated into cilia and flagella axonemes, which is required for their stability and maintenance. Flagella glycylation controls sperm motility. Both polyglutamylation and monoglycylation can coexist on the same protein on adjacent residues, and lowering glycylation levels increases polyglutamylation, and reciprocally.
The C-terminal phenylalanine residue is cleaved by KIAA0895L/MATCAP.