The many faces of aspartate kinases

► AK catalyzes the first step of the Asp-derived amino acid pathway in plants and microorganisms. ► AK is an enzyme showing a high diversity both in terms of allosteric properties and structural organization. ► Allosteric control in AK was acquired by addition of a regulatory domain containing 2 or 4 ACT domains. ► Various organizations of the ACT domains in AK have contributed to different mechanisms of allosteric controls.