X-ray crystallography has yielded electron density maps allowing the structure of the 50S in Haloarcula marismortui to be determined to 2. 4Å resolution and of the 50S in Deinococcus radiodurans to 3. 3Å. The large ribosomal subunit (50S) is approximately twice as massive as the small ribosomal subunit (30S). The model of Hm 50S, determined in 2000 by Nenad Ban and colleagues in the laboratory of Thomas Steitz and the laboratory of Peter Moore, includes 2711 of the 2923 nucleotides of 23S rRNA, all 122 nucleotides of its 5S rRNA, and structure of 27 of its 31 proteins.