• allophycocyanin;
  • cyanobacterium;
  • linker polypeptide;
  • Myxosarcina concinna;
  • phycobilisome;
  • phycocyanin

A phycocyanin (PC) and three allophycocyanin (AP) components (designated PC, AP1, AP2, and AP3) were prepared from Myxosarcina concinna Printz phycobilisomes by the native gradient PAGE performed in a neutral buffer system combined with the ion exchange column chromatography on DEAE-DE52 cellulose. PC contained one β subunit (inline image) and two α ones (inline image and inline image), and it carried two rod linkers (inline image and inline image) and one rod-core linker (inline image). AP1 and AP3 were characterized as peripheral core APs, whereas AP2 was an inner-core one. AP2 and AP3 were demonstrated to function as the terminal emitters. Each of the three APs contained two β subunits (inline image and inline image), two α subunits (inline image and inline image) and an inner-core linker (inline image). AP2 and AP3 had another subunit of the allophycocyanin B (AP-B) type (inline image) belonging to the β subunit group, and AP1 and AP3 carried their individual specific core linkers (inline image and inline image), respectively. No AP component was shown to associate with the core-membrane linker LCM. The functions of the linker polypeptides in the phycobilisome (PBS) construction are discussed.