hinge region

n.
  1. The portion of a crystalline form of tRNA that deforms to an L shape under electron microscopy.
  2. A short sequence of amino acids that lies at the base of each of the heavy chain regions of an immunoglobin and facilitates flexible movement of the molecule.
The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.