Tubulin binding cofactor A (IPR004226)

Short name: TBCA

Overlapping homologous superfamilies

Family relationships



The tubulin heterodimer consists of one alpha- and one beta-tubulin polypeptide. In humans, five tubulin-specific chaperones termed TBCA/B/C/D/E are essential for bring the alpha- and beta-tubulin subunits together into a tightly associated heterodimer. Following the generation of quasi-native beta- and alpha-tubulin polypeptides (via multiple rounds of ATP-dependent interaction with the cytosolic chaperonin), TBCA and TBCB bind to and stabilise newly synthesised beta- and alpha-tubulin, respectively. The exchange of beta-tubulin between TBCA and TBCD, and of alpha-tubulin between TBCB and TBCE, resulting in the formation of TBCD/beta and TBCE/alpha. These two complexes then interact with each other and form a supercomplex (TBCE/alpha/TBCD/beta). Interaction of the supercomplex with TBCC causes the disassembly of the supercomplex and the release of E-site GDP-bound alpha/beta tubulin heterodimer, which becomes polymerization competent following spontaneous exchange with GTP [PMID: 23973072].

This entry represents tubulin binding cofactor A (TBCA) from animal, plants and fungi. Human TBCA functions as a molecular chaperone for beta-tubulin [PMID: 12054808]. Budding yeast TBCA, also known as Rbl2, may bind transiently to free beta-tubulin, which then passes into an aggregated form that is not toxic [PMID: 11739729]. The sequence identity of Rbl2 and human TBCA is only 32%, they appear to be structurally distinct and may interact with beta-tubulin by different mechanisms [PMID: 15321725].

GO terms

Biological Process

GO:0007023 post-chaperonin tubulin folding pathway
GO:0007021 tubulin complex assembly

Molecular Function

GO:0048487 beta-tubulin binding

Cellular Component

No terms assigned in this category.

Contributing signatures

Signatures from InterPro member databases are used to construct an entry.