LiDS-PAGE (A and B) and absorption spectra (C, D, and E) of the main bands from the denaturing IEF gel shown in Fig. 8D, obtained from Synechococcus sp. strain M16.17 cells grown in blue light (BL) and white light (WL). The absorption spectra of bands i-a and i-b (present only in BL) were identical and very different from that of band i-c (C). The LiDS-PAGE analysis of band i-c (A) revealed that it was made up of two proteins, a minor (∼20-kDa) protein, CpeB, and a major (∼18-kDa) protein, MpeA, also found (pure) in bands i-a and i-b. Bands iii-a and iii-b contained a sole ∼19-kDa protein, MpeB (B).