Source:http://linkedlifedata.com/resource/umls/id/C1515032
NCI: A Substrate Domain is a protein region that physically interacts stereospecifically, and usually at high affinity, with a specific target substrate. In enzymes, the substrate domain is often, though not necessarily, coincident with the catalytic domain. Typically, substrate interaction results in some protein conformational alteration and functional modification. (NCI)