1. a homology unit; i.e., any of the three or four homologous regions of an immunoglobulin heavy chain that apparently evolved by duplication and diverged by mutation. 2. any discrete, continuous part of a polypeptide sequence that can be equated with a particular function. 3. a relatively short sequence of about 100 amino acids that adopts a defined three-dimensional structure within a protein. Also known as a module. 4. any region of a chromosome within which supercoiling is independent of other domains. 5. an extensive region of DNA including an expressed gene that exhibits pronounced sensitivity to degradation by endonucleases. See immunoglobulin domain superfamily, otu domain, SH domain.
Subjects: Genetics and Genomics.