constant region
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Related to constant region: hinge region
constant region
n.
The portion of an immunoglobulin molecule's heavy and light chains that determines the class or subclass of the immunoglobulin and that is almost identical in amino acid sequence in all molecules of a particular class or subclass.
American Heritage® Dictionary of the English Language, Fifth Edition. Copyright © 2016 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.