May help in the organization of the PsaE and PsaF subunits. PSI consists of a core antenna complex that captures photons, and an electron transfer chain that converts photonic excitation into a charge separation. The eukaryotic PSI reaction center is composed of at least 11 subunits. Only detected in green leaves and not etioplasts; PSI is only assembled in green leaves (PubMed:19137553). Belongs to the PsaJ family.