About TTC / Tetratricopeptide Repeat Domain:
TTC, also known as Tetratricopetide repeat proteins, is a series of proteins that are encoded by the TTC1, TTC3, TTC4, TTC5, TTC6, TTC7A, TTC7B, TTC8, TTC9C, TTC12, TTC13, TTC14, TTC15, TTC16, TTC17, TTC18, TTC21A, TTC21B, TTC22, TTC24, TTC25, TTC27, TTC28, TTC29, TTC30A, TTC30B, TTC31, TTC33, and TTC37 genes. They are examples of genes that feature the tetratricopeptide repeat structure motif.
How TTC proteins function remains, by and large, unclear. Some of them play a role in Cilia formation and function, with many of them showing roles in protein complex formation. Nine of them are known as components of IFT or BBSome complexes.
Tetratricopeptide Repeat Domain Mechanism
The specifics of the exact molecular mechanism of the TTC proteins are unknown, and they are each likely to have their own mechanisms.
There are various interactions between the TTC proteins and other genes. TTC1 is known to interact with TRIP6 (Thyroid Hormone Receptor Interactor 6), TTLL12 (Tubulin Tyrosine Ligase Like 12), ZRANB2 (Zinc Finger RANBP2-Type Containing 2), UBE2B (Ubiquitin Conjugating Enzyme E2 B), and SSSCA1 (Zinc Ribbon Domain Containing 2).
TTC3 interacts with UBE2D2 (Ubiquitin Conjugating Enzyme E2 D2), UBC (Ubiquitin C), AKT1 (AKT Serine/Threonine Kinase 1), AKT3 (AKT Serine/Threonine Kinase 2), and DYNC2LI1 (Dynein Cytoplasmic 2 Light Intermediate Chain 1).
There are several more TTC proteins, each with its own interactions.
Tetratricopeptide Repeat Domain Structure
The structures of the various TTC genes differ, but a typical structure is characterized by interactions between helices A and B of the first motif and helix A’ of the next TPR.