| β IV tubulin, encoded by TUBB4A, is a brain-enriched β-tubulin isotype that belongs to the family of guanosine triphosphate–binding tubulin proteins forming α/β heterodimers, the basic subunits of microtubules. The protein contributes to the dynamic microtubule lattice that supports cell shape, vesicle movement, organelle positioning, and mitotic spindle function, while its isotype-specific expression pattern gives it a prominent role in the nervous system and oligodendroglial microtubule organization. In developing white matter, β IV tubulin appears in premyelinating oligodendrocytes and becomes abundant in myelinating oligodendrocyte perinuclear cytoplasm and cellular processes that extend along developing myelin internodes, where it is distributed diffusely rather than in a centrosome-centered array. This localization matches a microtubule network that supports transport of myelin proteins, lipids, and RNA during myelin formation, and the same isotype persists in oligodendrocyte lineage cells with a pattern that aligns with process extension and internode growth. The TUBB4A product participates in heterodimer assembly with α-tubulin and incorporation into microtubules that undergo GTP-dependent polymerization and depolymerization, linking the protein to the structural plasticity required for neuronal morphology and glial process remodeling. Tubulin isotype usage is not uniform, and β IV tubulin forms part of the “multi-tubulin” repertoire that supports specialized microtubule functions in particular neural cell populations rather than a single generic cytoskeletal role. Pathogenic TUBB4A variants disrupt this isotype-specific microtubule program and associate with hypomyelinating leukodystrophy, basal ganglia and cerebellar atrophy, and dystonia, with phenotypes that reflect altered white matter maintenance and neuronal support. Mutant TUBB4A is also linked to abnormal microtubule accumulation in oligodendrocytes and loss of myelin integrity, placing the protein at the center of disorders defined by impaired cytoskeletal organization and defective myelination. |
