Required for the insertion of some light harvesting chlorophyll-binding proteins (LHCP) into the chloroplast thylakoid membrane. Plays a role in the accumulation of some cytochrome b6f components in the thylakoid membrane (PubMed:26265777). Required for the assembly and/or stability of the F(1)F(0) ATP synthase in chloroplast thylakoid membranes. Functions to stabilize or promote assembly of F(1) during its attachment to the membrane-embedded F(0) part (PubMed:19995738). Participates with STIC2 in thylakoid protein targeting. May function with a specific subset of thylakoidal proteins (PubMed:28684427). Homodimer (PubMed:28684427). Interacts with ALB3 (PubMed:26265777). Interacts with STIC2 (PubMed:28684427). A number of isoforms are produced. According to EST sequences. Highly expressed in green tissues. No visible macroscopic phenotype under normal growth condtions. Increased number of plastoglobules (lipid bodies) in chloroplasts. Belongs to the OXA1/ALB3/YidC (TC 2.A.9.2) family. Was originally thought to be the product of one gene (ARTEMIS) that in fact corresponds to two separate genes At1g24485 and At1g24490.