Tubulin-folding cofactor B

Tubulin-folding cofactor B (TBCB) is a 244-amino-acid chaperone protein that facilitates the folding of alpha-tubulin heterodimers after their interaction with cytosolic chaperonin complexes (UniProt: Q99426). It binds tubulin folding intermediates and regulates the dissociation of properly folded tubulin heterodimers, with potential roles in negative regulation of axonal growth.

TBCB operates within cytosolic chaperone pathways essential for proper microtubule assembly and neuronal cytoskeletal organization. No disease associations are documented in the UniProt record (UniProt: Q99426).

In Alzheimer's Disease, TBCB shows ambiguous regulation across subcellular fractions (Chaparral AD proteomics). A post-mortem AD brain versus age-matched control comparison using TMT-labeled proteomics across four subcellular fractions (P2, P3, S2, S3) yielded a mean log2 fold-change of −0.13, indicating minimal overall change but compartment-specific directionality. This modest downregulation or stability across fractions suggests TBCB alterations are not prominent features of the AD proteome signature.