Summary of MHC Class II Molecule Properties
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	MHC class II molecules are heterodimers composed of an a and a b subunit.
	The a subunit is a 33 kDa polypeptide and the b subunit is 28kDa.   Both subunits are inserted in the membrane, and are encoded by the MHC.
	The membrane-distal, N-terminal structural domains of the a subunit and the b subunit - i.e.,  a1 and b1 - associate to form the peptide-binding pocket and the membrane-distal region of the molecule.
	The membrane-proximal, C-terminal structural domains of the a subunit and the b subunit - i.e.,  a2 and b2 - associate to form the CD4 binding site of the molecule.
	MHC class II ab exhibit a tendency to self-associate forming (ab)2 "dimers of dimers".

© Duane W. Sears
29 August, 2009