selection seems to act in two ways : -- horizontally , in a multigene system such as the immunoglobulin classes ( c domains of the heavy chains ) , leading to interclass homologies which are particularly marked for all the cooh-terminal domains of h and l chains which have , in addition a fair degree of homology with human beta2 microglobulin ( about 30 % identities ) ;
C0086418
human
C1417683
beta2