| description | A globular structural motif found in many proteins of the immune system, including immunoglobulins (Igs), T cell receptors (TCRs) and major histocompatibility complex (MHC) molecules. Ig domains are approximately 110 amino acid residues in length, include an internal disulfide bond, and contain two layers of beta-pleated sheets, each layer composed of three to five strands of antiparallel polypeptide chains. Ig domains are classified as V-like or C-like on the basis of closest homology to either Ig V or C domains |
