<p>This entry contains the photosystem II P680 chlorophyll A apoprotein, PsbB.</p><p>Photosystem II light-harvesting proteins are the intrinsic transmembrane antenna proteins CP43 (PsbC) and CP47 (PsbB) found in the reaction centre of PSII. These polypeptides bind to chlorophyll a and beta-carotene and pass the excitation energy on to the reaction centre [<cite idref="PUB00015360"/>]. This family also includes the iron-stress induced chlorophyll-binding protein CP43 (IsiA), which evolved in cyanobacteria from a PSII protein to cope with light limitations and stress conditions [<cite idref="PUB00015361"/>]. </p> Photosystem II PsbB