The antenna complex functions as a light receptor, it captures and delivers excitation energy to photosystems II and I. The Prochlorales pcb genes are not related to higher plant LHCs. The antenna complex consists of divinyl chlorophylls (a and b) and divinyl chlorophyll a/b binding proteins and binds more divinyl chlorophyll b than does the antenna complex from high-light-adapted Prochlorococcus. This transcript is strongly expressed between 4.5 and 72 umol blue light/m2/s. The whole antenna complex is most highly expressed under low light; as the light levels increase antenna complex levels decrease. Thus at least in this strain the amount of antenna complex is controlled mostly at a post-transcriptional level. Transcription decreases upon iron starvation. This low-light-adapted strain contains 8 pcb genes. Belongs to the PsbB/PsbC family. IsiA/Pcb subfamily.