Part of a complex that function as an ATP-dependent zinc metallopeptidase. Involved in the thylakoid formation and in the removal of damaged D1 in the photosystem II, preventing cell death under high-intensity light conditions. Binds 1 zinc ion per subunit. Heterohexamers with FTSH1, FTSH2 and FTSH5. May also form homooligomers. Expressed in cotyledons, cauline and rosette leaves, stems, sepals, flovers and siliques. Very low in roots. By heat and high light. The conserved lumenal (CL) domain (74-154) is present only in some FtsH homologs from organisms performing oxygenic photosynthesis. No visible changes in phenotype, probably due to a complementation by FTSH2. The presence of both FTSH1 or FTSH5 (subunit type A) and FTSH2 or FTSH8 (subunit type B) is essential for an active complex formation. In the N-terminal section; belongs to the AAA ATPase family. In the C-terminal section; belongs to the peptidase M41 family.