FLU is a negative regulator of chlorophyll biosynthesis. It directly binds to glutamyl-tRNA reductase to prevent the over-accumulation of tetrapyrroles in chloroplasts.
ATAB2 is a chloroplast-localized protein. ATAB2 is involved in the biogenesis of Photosystem I and II. ATAB2 has A/U-rich RNA-binding activity and presumably functions as an activator of translation with targets at PS I and PS II.