Which of the following is true about isotypic variation- (AIIMS Nov 09)
|A||Subtle changes in AA sequence due to allelic difference|
|B||Changes in a heavy and light chain in variable region|
|C||Changes in heavy and light chain in constant region responsible for class and subtype|
|D||These are areas in antigen that bind specifically to antibody|
a. Isotypes are antigenic determinants that characterize classes and subclasses of heavy chains and types and subtypes of light chains, located in the constant parts of heavy chains.
b. Subtle changes in AA sequence due to allelic difference is allotype variation. Allotypes are known for all the gamma and alpha heavy chains and kappa light chains. These allelic differences occur within a species.
c. Changes in a heavy and light chain in variable region which determine antigen binding is idiotype variation.