Superantigen binding to MHC II

Crystal Structure Of A Superantigen Bound To The High- Affinity, Zinc-Dependent Site On MHC Class II molecule

At present a wire frame image of the structure of the proteins is shown

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Superantigens are not processed by a cell but bind to the class II MHC protein and to the V beta chain of the T cell
receptor in a different way from a presented peptide. You can identify the alpha and beta chains of the MHC molecule by changing them to space-fill or another from using the buttons below. Note that MHC alpha chain interacts with the superantigen but binding is on the outside of the MHC molecule rather than the interior site formed by both the alpha and beta chains at which a processed peptide binds. You can see this peptide site by changing the peptidomimetic inhibitor (which binds to the peptide site) using the buttons below

A given superantigen activates a distinct class of T cells that express a certain V beta chain. The binding of super antigen to the chains of the T cell receptor is shown here

Compare the interaction of the superantigen that you see here with the way a processed peptide interacts with the MHC II and TCR molecules here

Further changes and selections may be made using the Chime menu. Right click on the molecule to show the Chime menu.

Protein Data Bank entry here

	MHC II alpha chain (dark blue) Backbone Space Fill Ribbons Wife frame	MHC II beta chain (light blue) Backbone Space Fill Ribbons Wife frame
	Peptidometic inhibitor (red) Backbone Space Fill Wire frame	Bacterial superantigen (seb) (green) Backbone Space Fill Ribbons Wife frame

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