User:Alice Harmon/Sandbox 2

CDPKCDPK

Calcium-dependent protein kinases (CDPKs) are found in plants, algae, and apicomplexan protists, such as the parasites that cause malaria and toxoplasmosis. They are monomeric enzymes containing an amino-terminal protein kinase domain linked to a carboxy-terminal calcium-binding domain, that has sequence similarity to calmodulin. CDPKs belong to the calmodulin-dependent protein kinase family.

Crystal structures of inactive and active conformations of CDPK1 from Toxoplasma gondii show the dramatic conformation change that occurs upon the binding of calcium to the regulatory domain .

spinqualitylabelsall models 3hx4 - active TgCDPK1 Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image

spinqualitylabelsall models 3ku2 - inactive TgCDPK1 Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image

The crystal structure 3hx4 in the left scene shows the of the kinase that is bound to calcium (green spheres) and the ATP analog ANP (also called AMPPNP; shown in wireframe and CPK coloring). The catalytic domain is blue and the calcium activation domain (CAD) is gold. In the kinase domain, ANP sits in the catalytic cleft between the large and small lobes of the domain. CAD is bound to the side of the kinase opposite to the catalytic cleft, making it available for peptide substrate binding.

The crystal structure 3ku2 in the right scene shows the inactive conformation of the kinase that is bound only to the ANP (wireframe and CPK coloring). As above, the catalytic domain is blue and the CAD is gold. Note the large conformational change in the CAD (long alpha helices), and that it is bound to the same side of the kinase as the catalytic cleft, blocking it from binding peptide substrate.