PROSITE documentation PDOC00262
Immunoglobulins and major histocompatibility complex proteins signature


The basic structure of immunoglobulin (Ig) [1] molecules is a tetramer of two light chains and two heavy chains linked by disulfide bonds. There are two types of light chains: kappa and lambda, each composed of a constant domain (CL) and a variable domain (VL). There are five types of heavy chains: α, delta, epsilon, γ and mu, all consisting of a variable domain (VH) and three (in α, delta and γ) or four (in epsilon and mu) constant domains (CH1 to CH4).

The major histocompatibility complex (MHC) molecules are made of two chains. In class I [2] the α chain is composed of three extracellular domains, a transmembrane region and a cytoplasmic tail. The β chain (β-2-microglobulin) is composed of a single extracellular domain. In class II [3], both the α and the β chains are composed of two extracellular domains, a transmembrane region and a cytoplasmic tail.

It is known [4,5] that the Ig constant chain domains and a single extracellular domain in each type of MHC chains are related. These homologous domains are approximately one hundred amino acids long and include a conserved intradomain disulfide bond. We developed a small pattern around the C-terminal cysteine involved in this disulfide bond which can be used to detect these category of Ig related proteins.

Last update:

April 2006 / Pattern revised.


Technical section

PROSITE method (with tools and information) covered by this documentation:

IG_MHC, PS00290; Immunoglobulins and major histocompatibility complex proteins signature  (PATTERN)


1AuthorsGough N.
SourceTrends Biochem. Sci. 6:203-205(1981).

2AuthorsKlein J. Figueroa F.
SourceImmunol. Today 7:41-44(1986).

3AuthorsFigueroa F. Klein J.
SourceImmunol. Today 7:78-81(1986).

4AuthorsOrr H.T. Lancet D. Robb R.J. Lopez de Castro J.A. Strominger J.L.
TitleThe heavy chain of human histocompatibility antigen HLA-B7 contains an immunoglobulin-like region.
SourceNature 282:266-270(1979).
PubMed ID388231

5AuthorsCushley W. Owen M.J.
SourceImmunol. Today 4:88-92(1983).

6AuthorsBeck S. Barrell B.G.
TitleHuman cytomegalovirus encodes a glycoprotein homologous to MHC class-I antigens.
SourceNature 331:269-272(1988).
PubMed ID2827039

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