A PSA4-YCF4 complex promotes assembly of the photosystem I reaction center in Arabidopsis.
This work has identified and characterized PSA4 (Photosystem I Assembly 4), a thylakoid membrane protein conserved in land plants and green algae and proposed that PSA4 and YCF4 form a dedicated complex that promotes the assembly of the PsaA/PsaB heterodimer during the early steps of PSI biogenesis in chloroplasts.