Reviewer: S. Randhawa, M.D., Allergist/Immunologist and Assistant Professor at LSU (Shreveport) Department of Allergy and Immunology
Cytokine Receptors include the following types:
- Type I (hematopoietin receptors - IL-3 and Epo)
- Type II
- IL-1 family receptors - they share Toll-like/IL-1 receptor (TIR) domain
- TNF receptors
- Seven-transmembrane α-helical receptors
(click to enlarge the image)
Type I Cytokine Receptors
Type I are hemopoietin receptors, contain a domain with two cysteine residues and a sequence of tryptophan-serine-X-tryptophan-serine (WSXWS), where X is any amino acid. Bind cytokines that fold into four α-helical strands - type I cytokines.
All type I and type II cytokine receptors engage Jak-STAT signaling pathways.
Receptors for IL-2, IL-4, IL-7, IL-9, IL-15, and IL-21 contain γ chain, which is affected in X-linked SCID.
Type II Cytokine Receptors
Type II are similar to type I (two extracellular domains with conserved cysteines) but do not contain the WSXWS motif. These receptors consist of one ligand-binding polypeptide chain and one signal-transducing chain.
All type I and II cytokine receptors engage Jak-STAT signaling pathways.
IL-1 family receptors
IL-1 family receptors share a cytosolic sequence, called the Toll-like/IL-1 receptor (TIR) domain.
TNF receptors are part of a large family of proteins (some of which are not cytokine receptors) with trimeric, cysteine-rich extracellular domains.
G protein-coupled receptors
Seven-transmembrane α-helical receptors are also called serpentine receptors, because their transmembrane domains "snake" back and forth through the membrane. Also called G protein-coupled receptors because their signaling pathways involve guanosine triphosphate (GTP)-binding proteins (G proteins). Involved in many types of cellular responses and typically produce a rapid and transient response.
Cellular and Molecular Immunology, Abbas et al., 2009.