This domain is found in protein phosphatase 2C, as well as other proteins eg. pyruvate dehydrogenase (lipoamide)]-phosphatase and adenylate cyclase .
Protein phosphatase 2C (PP2C) is one of the four major classes of mammalian
serine/threonine specific protein phosphatases . PP2C  is a monomeric enzyme of about 42 Kd which shows broad substrate specificity and is dependent on divalent cations (mainly manganese and magnesium) for its activity. Its exact physiological role is still unclear. Three isozymes are currently known in mammals: PP2C-alpha, -beta and -gamma. In yeast, there are at least four PP2C homologs: phosphatase PTC1 , which has weak tyrosine
phosphatase activity in addition to its activity on serines, phosphatases PTC2
and PTC3, and hypothetical protein YBR125c. Isozymes of PP2C are also known from Arabidopsis thaliana (ABI1, PPH1), Caenorhabditis elegans (FEM-2, F42G9.1, T23F11.1), Leishmania chagasi and Paramecium tetraurelia. In A. thaliana, the kinase associated protein phosphatase (KAPP)  is an enzyme that dephosphorylates the Ser/Thr receptor-like kinase RLK5 and which contains a C-terminal PP2C domain.
PP2C does not seem to be evolutionary related to the main family of serine/
threonine phosphatases: PP1, PP2A and PP2B. However, it is significantly similar to the catalytic subunit of pyruvate dehydrogenase phosphatase (PDPC) , which catalyzes dephosphorylation and concomitant reactivation of the alpha subunit of the E1 component of the pyruvate dehydrogenase complex. PDPC is a mitochondrial enzyme and, like PP2C, is magnesium-dependent.