[′krȯs rē‚ak·tiŋ mə′tir·ē·əl] (biochemistry) A protein produced by a mutant gene that is enzymatically inactive but shows serological properties similar to the protein of the wild-type gene.
cross-reacting material
cross-re·act·ing ma·te·ri·al (CRM),
a substance sufficiently different from a reference substance (R) to have a perceptibly different function from R, but similar enough to react with anti-R antibodies.