Tubulin Folding Cofactor

TPPP3 is a member of the TPPP family and is found in the cytoplasm. TPPP3 binds tubulin, has microtubule bundling activity takes part in mitosis and cell proliferation.

TBCEL, is a factor that is in charge of the microtubule cytoskeleton in determining cell behavior. TBCEL plays a role as a regulator of tubulin stability. While widely expressed in testis, TBCEL is also present in several tissues at a much lower level. TBCEL comprises of seven LRR (leucine-rich) repeats, one LRRCT domain and one ubiquitin-like domain. The gene that translates TBCEL consists of 66,704 bases and maps to human chromosome 11q23.3. Chromosome 11 houses over 1,400 genes and consist of nearly 4% of the human genome. Jervell and Lange-Nielsen syndrome, Jacobsen syndrome, Niemann-Pick disease, hereditary angioedema and Smith-Lemli-Opitz syndrome are associated with defects in genes that map to chromosome 11.

Tubulin folding cofactor C (TBCC) is a member of the TBCC family. TBCC has a role in the control of centrosome and Golgi apparatus positioning, with effects on cell shape and cell migration. Cofactor C is 1 of 4 proteins (cofactors A,D,E and C) engaged in the pathway leading to properly folded b-tubulin from folding intermediates. Cofactor E attaches to the cofactor D/beta-tubulin complex; their interaction with cofactor C subsequently causes the release of beta-tubulin polypeptides which are bound to the native state.

TBCB is a member of the Microtubules family. Biosynthesis of functional microtubules include the involvement of a number of chaperones, termed Tubulin folding cofactors A (TBCA), B (TBCB), C (TBCC), D (TBCD) and E (TBCE), which operate on folding intermediates downstream of the cytosolic chaperon, known as TCP. The 244 amino acid cytoplasmic protein TBCB has one CAP-Gly domain and is universally expressed. TBCB takes part in the regulation of tubulin heterodimer dissociation and operates as a negative regulator of axonal growth.

TBCA is a tubulin-folding protein which is involved in the early step of the tubulin folding pathway. TBCA is one of four proteins (cofactors A, D, E, and C) implicated in the pathway directing to properly folded beta-tubulin from folding intermediates. Cofactors A and D are thought to be a factor in capturing and stabilizing beta-tubulin in a quasi-native confirmation. TBCA is crucial for cell viability, if reduced it causes a decrease in the amount of soluble tubulin, alterations in microtubules and G1 cell cycle arrest. Cofactor E attaches to the cofactor D-tubulin complex, afterward, interaction with cofactor C triggers the release of tubulin polypeptides that are committed to the native state.