Binds specific group II introns in chloroplasts and facilitates their splicing. Acts on both subgroup IIA and subgroup IIB introns. The substrates of the subgroup II also require the CRM domain proteins CAF1 or CAF2. Binds both single-stranded and double-stranded RNA non-specifically, but lacks endonuclease activity. Required for plastid ribosome biogenesis. Interacts with RNA. Part of large ribonucleo-protein particles that contain CAF1 and/or CAF2. Pale green, albino, and albino stunted seedling phenotypes. Lack of plastid ribosomes.