The CBS domain is composed of a beta-alpha-beta-beta-alpha secondary structure pattern that is folded into a globular tertiary structure that contains a three-stranded antiparallel β-sheet with two α-helices on one side.
 CBS domains are always found in pairs in protein sequences and each pair of these domains tightly associate in a pseudo dimeric arrangement through their β-sheets forming a so-called CBS-pair or Bateman domain.
These CBS domain pairs can associate in a head-to-head (i.e. PDB codes 3KPC​, 1PVM​, 2OOX​) or a head-to-tail (i.e. PDB codes 1O50​, 1PBJ​) manner forming a disk-like compact structure.
By doing so, they form clefts that constitute the canonical ligand binding regions.
In principle, the number of canonical binding sites matches the number of CBS domains within the molecule and are traditionally numbered according to the CBS domain that contains each of the conserved aspartate residues that potentially interact with the ribose of the nucleotides.
However, not all of these cavities might necessarily bind nucleotides or be functional.
Recently, a non-canonical site for AMP has also been described in protein MJ1225 from M. jannaschii, though its functional role is still unknown.
The CBS domain is composed of a beta-alpha-beta-beta-alpha secondary structure pattern that is folded into a globular tertiary structure that contains a three-stranded antiparallel β-sheet with two α-helices on one side.  CBS domains are always found in pairs in protein sequences and each pair of these domains tightly associate in a pseudo dimeric arrangement through their β-sheets forming a so-called CBS-pair or Bateman domain. These CBS domain pairs can associate in a head-to-head (i.e. PDB codes 3KPC​, 1PVM​, 2OOX​) or a head-to-tail (i.e. PDB codes 1O50​, 1PBJ​) manner forming a disk-like compact structure. By doing so, they form clefts that constitute the canonical ligand binding regions. In principle, the number of canonical binding sites matches the number of CBS domains within the molecule and are traditionally numbered according to the CBS domain that contains each of the conserved aspartate residues that potentially interact with the ribose of the nucleotides. However, not all of these cavities might necessarily bind nucleotides or be functional. Recently, a non-canonical site for AMP has also been described in protein MJ1225 from M. jannaschii, though its functional role is still unknown.
CBS domain