Interactions between the Allochromatium tepidum LH1 α-polypeptides and the RC C-subunit.A, side view of the α3-polypeptide (orange surface) entangled with the RC C-subunit (light-cyan surface) through its long C-terminal domain. B, side view of the an α1-polypeptide (green surface) interacting with the RC C-subunit through its C-terminal domain. C, illustrations of interactions in the C-terminal domains of α3- and α1-polypeptides with the RC subunits. LH1, light-harvesting complex; RC, reaction center.