constant region

The portion of the amino acid sequence of an antibody's heavy or light chains that determines the class of the antibody and does not vary within a given class. The constant region terminates in a free carboxyl group (COOH). Unlike the variable region, the constant region does not interact with antigens. Compare variable region.

Nearby words

  1. constant dollar,
  2. constant dollars,
  3. constant of gravitation,
  4. constant of integration,
  5. constant positive pressure breathing,
  6. constant, benjamin,
  7. constant-velocity joint,
  8. constantan,
  9. constantia,
  10. constantine

The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.