Required for the insertion of integral membrane proteins into the membrane. Probably plays an essential role in the integration of proteins of the respiratory chain complexes. Involved in integration of membrane proteins that insert dependently and independently of the Sec translocase complex (By similarity). Addition of green fluorescent protein (GFP) to the C-terminus leads to photoinhibition at 80 umol/m(2)/s light intensity, reduced amounts of pigment, altered energy transfer between the antenna systems and the reaction centers of PSI and PSII, and impaired integration of PSII reaction center protein D1 (psbA) into membranes, suggesting it probably also aids protein insertion, folding and/or assembly of membrane complexes destined for the thylakoid (PubMed:15498761, PubMed:16905652). Specifically interacts with transmembrane segments of nascent integral membrane proteins during membrane integration (By similarity). Interacts with the precursor of PSII reaction center D1 (PubMed:16905652). Coimmunoprecipitates with CyanoP (tlr2075), FtsH2, FtsH3, Phb1 (slr1106), Ycf39 and Ycf48 (PubMed:30061392). Merodiplod cells have greatly altered thylakoid morphology, and about 40% photosynthetic pigements, photosynthetic electron transport and oxygen evolution. Belongs to the OXA1/ALB3/YidC family. Type 1 subfamily.