Antenna complexes are light-harvesting systems, which transfer the excitation energy to the reaction centers. An alpha/beta heterodimer conjugated to 3 bacteriochlorophyll molecules. The core complex is formed by different alpha and beta chains, binding bacteriochlorophyll molecules, and arranged most probably in tetrameric structures disposed around the reaction center. The non-pigmented gamma chains may constitute additional components (By similarity). An active antenna complex lacking the last 16 residues has also been isolated from DSM 149. Belongs to the antenna complex alpha subunit family.