Part of the twin-arginine translocation (Tat) system that transports large folded proteins containing a characteristic twin-arginine motif in their signal peptide across the thylakoid membrane. Involved in delta pH-dependent protein transport required for chloroplast development, especially thylakoid membrane formation. TATC and TATB mediate precursor recognition, whereas TATA facilitates translocation. In thylakoid membranes, TATC and TATB form a large receptor complex, containing about eight TATC-TATB pairs, which binds the precursor protein. Twin arginine signal peptide promotes pH-triggered docking of TATA oligomers to TATC-TATB receptor complex, inducing a conformational switch of TATA that results in activation of the translocase. TATA dissociates from TATC-TATB upon completion of translocation. The N-terminus is located in the stroma. Seedling lethality when homozygous. When grown on agar medium, mutant seedlings have an albino phenotype and contain plastid lacking internal membrane structures. According to PubMed:18930082, TATA is detectable only in minor amounts in Arabidopsis chloroplasts. Belongs to the TatC family.