IMGT Index

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Superfamily

A superfamily is defined structurally, and not functionally, or on sequence similarity.

In IMGT, two superfamilies are defined:

the immunoglobulin superfamily (IgSF)
the major histocompatibility superfamily (MhcSF).

A protein belongs to the IgSF if the amino acid chain includes at least one domain with an "Ig fold". In IMGT, these domains are described:

for IG and TR, as V-DOMAIN and C-DOMAIN,
for proteins other than IG and TR, as V-LIKE-DOMAIN and C-LIKE-DOMAIN.

Any protein with, at least, a V-DOMAIN, C-DOMAIN, V-LIKE-DOMAIN or C-LIKE-DOMAIN belongs to the IgSF.

A protein belongs to the MhcSF if the amino acid chain includes at least one domain with a helix and beta sheet that form "half of a Mhc cleft". In IMGT, these domains are described:

for MHC, as G-DOMAIN,
for proteins other than MHC, as G-LIKE-DOMAIN.

Any protein with, at least, a G-DOMAIN or a G-LIKE-DOMAIN belongs to the MhcSF.

The MHC-I-Alpha and MHC-II chains belong both to the MhcSF, by their G-DOMAIN(s), and to the IgSF, by their C-LIKE-DOMAIN.
The MHC-I-Alpha-like chains belong both to the MhcSF, by their G-LIKE-DOMAIN(s), and to the IgSF, if the C-LIKE-DOMAIN is present.
For examples: Human CD1A, Mouse CD1D1.

See also:

More information:

IMGT Repertoire (RPI)

Created: 09/10/2003
Last updated: Wednesday, 29-Jun-2011 17:02:00 CEST
Author: Marie-Paule Lefranc
Editors: Céline Protat, Chantal Ginestoux
Contact: Marie-Paule Lefranc

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