Tubulin beta-4B chain

Tubulin beta-4B chain (TUBB4B) is a core structural protein that forms heterodimers with alpha-tubulin to assemble microtubules, the cylindrical scaffolds essential for intracellular transport and cellular architecture (UniProt: P68371). GTP binding and hydrolysis drive microtubule polymerization dynamics, with alpha-tubulin providing the catalytic activity for this process.

TUBB4B is expressed broadly across tissues and is primarily associated with Leber congenital amaurosis with early-onset deafness (LCAEOD), an autosomal dominant disorder causing severe retinal degeneration and sensorineural hearing loss in early childhood (UniProt: P68371). The protein's structural role in microtubules is fundamental to numerous cellular pathways including neuronal development and vesicular trafficking.

In Alzheimer's disease, TUBB4B shows ambiguous directional change across subcellular fractions in post-mortem AD brain compared to age-matched controls (Chaparral AD proteomics). Quantitative proteomics using tandem mass tag labeling across four subcellular fractions yielded a mean log2 fold-change of −0.21, indicating modest overall downregulation, though the directional inconsistency across fractions suggests compartment-specific dysregulation rather than uniform change.