Here you are: IMGT Web resources > IMGT Index

Receptor type

A receptor type is defined when one chain or several associated chains (usually covalently linked) are considered as a unit (monomer) with known (or putative) binding property for a ligand. Chains of a receptor are designated as partners. In other terms, a receptor is a protein with known (or putative) binding function.

The 'receptor type' concept is part of the 'IDENTIFICATION' axiom of IMGT-ONTOLOGY [1].

In IMGT, receptor types are defined for the Immunoglobulins (IG), T cell receptors (TR), major histocompatibility (MH), related proteins of the immune system (RPI) and fusion proteins for immune applications (FPIA).

Click here for a list of the IG, TR and MH receptor types and for examples of RPI and FPIA, in IMGT/PROTEIN-DB and IMGT/3Dstructure-DB. This table also provides the chain types and their standardized labels.

Immunoglobulins (IG)

An IG receptor corresponds to a complete immunoglobulin or antibody, with 2 identical IG heavy chains and 2 identical IG light chains linked by interchain disulfide bridges.

An IG 'receptor type' is identified by the IG receptor class, or subclass (1), taking into account the light chain type (2).

There are eighteen instances for the IG 'receptor type', in human:

  • IgA1-Kappa
  • IgA2-Kappa
  • IgD-Kappa
  • IgE-Kappa
  • IgG1-Kappa
  • IgG2-Kappa
  • IgG3-Kappa
  • IgG4-Kappa
  • IgM-Kappa
  • IgA1-Lambda
  • IgA2-Lambda
  • IgD-Lambda
  • IgE-Lambda
  • IgG1-Lambda
  • IgG2-Lambda
  • IgG3-Lambda
  • IgG4-Lambda
  • IgM-Lambda

By extension, in vitro constructs derived from IG with known (or putative) binding property are also instances of the 'receptor type' concept:

Information on the chain type may eventually be added. Examples:

T cell receptors (TR)

A TR receptor corresponds to a dimer of 2 different chains linked, in most cases, by interchain disulfide bridges.

A TR 'receptor type' is identified by its two chains (2).

There are four instances for the TR 'receptor type', in human:

By extension, in vitro constructs derived from TR with known (or putative) binding property are also instances of the TR 'receptor type' concept. For example:

Major histocompatibility (MH)

A MH receptor corresponds to a dimer of 2 different chains.

A MH 'receptor type' is identified by its two constitutive chains.

There are two main instances for the MH 'receptor type':

Related proteins of the immune system (RPI)

A RPI corresponds to a protein receptor other than IG, TR or MH and with a function in the immune system. Many RPI belongs to the IgSF and MhSF.

Fusion proteins for immune applications (FPIA)

Fusion proteins for immune applications (FPIA) result generally from the fusion of one or several region and/or domain of protein(s) with the Fc of an IG in a '(protein)2:Fc' format. The Fc is used for its effector properties. They are currently designated with the suffix (stem) '-cept' in INN.

FPIA (Fusion proteins for immune applications) and CPCA (Composite proteins for clinical applications) correspond to in vitro engineered proteins of the WHO/INN programme. These categories FPIA and CPCA will be proposed for the INN definition in publication lists.

IMGT notes:
(1) An IG receptor class or subclass is identified by the heavy chain type, not taking into account the light chain type. There are five IG classes in human (IgA, IgD, IgE, IgG and IgM) and six subclasses (IgA1, IgA2, IgG1, IgG2, IgG3 and IgG4).
(2) In IMGT/LIGM-DB, the IG or TR 'receptor type' (e.g IgA-Kappa, TR-Alpha_Beta) is assigned to nucleotide sequences when the 'chain type' of both polypeptides of the receptor has been unambiguously identified.
Reference:
[1] Giudicelli, V. and Lefranc, M.-P., Bioinformatics, 15, 1047-1054 (1999) PMID:10745995, LIGM:221 pdficon
See also:
More information: