An enzyme-linked receptor, also known as a catalytic receptor, is a transmembrane receptor, where the binding of an extracellular ligand causes enzymatic activity on the intracellular side. Hence a catalytic receptor is an integral membrane protein possessing both catalytic, and receptor functions.
They have two important domains, an extra-cellular ligand binding domain and an intracellular domain, which has a catalytic function; and a single transmembrane helix. The signaling molecule binds to the receptor on the outside of the cell and causes a conformational change on the catalytic function located on the receptor inside the cell.
Examples of the enzymatic activity include: Receptor tyrosine kinase, as in fibroblast growth factor receptor. Most enzyme-linked receptors are of this type. Serine/threonine-specific protein kinase, as in bone morphogenetic protein Guanylate cyclase, as in atrial natriuretic factor receptor
Types
The following is a list of the five major families of catalytic receptors:
Family Member Gene Catalytic activity Endogenous ligands Synthetic ligands Erb ErbB1 (epidermal growth factor receptor) tyrosine kinase Epidermal growth factor, amphiregulin, betacellulin, epigen, epiregulin, HB-EGF, TGFa GW583340, gefitinib, erlotinib, tyrphostins AG879 and AG1478 ErbB2 " ErbB3 " NRG-1, NRG-2 GW583340, gefitinib, erlotinib, tyrphostins AG879 and AG1478 ErbB4 " Betacellulin, epiregulin, HB-EGF, NRG-1, NRG-2, NRG-3, NRG-4 GW583340, gefitinib, erlotinib, tyrphostins AG879 and AG1478 GDNF (glial cell-derived neurotrophic factor) GFRa1 " GDNF > neurturin > artemin GFRa2 " Neurturin > GDNF GFRa3 " Artemin GFRa4 " Persephin NPR (natriuretic peptide receptor) NPR1 guanylyl cyclase Atrial natriuretic peptide NPR2 " C-type natriuretic peptide NPR3 " Atrial natriuretic peptide NPR4 " Uroguanylin trk neurotrophin receptor TrkA tyrosine kinase Nerve growth factor > NT-3 GW441756, tyrphostin AG879 TrkB " Brain-derived neurotrophic factor, NT-4/NT-5 > NT-3 TrkC " NT-3 p75 " NGF, BDNF, NT3, NT4/5 Toll-like TLR1 " TLR2 " Peptidoglycan TLR3 " polyIC, polyinosine-polycytosine TLR4 " LPS, lipopolysaccharide derived from Gram-negative bacteria TLR5 " Flagellin TLR6 " TLR7 " resiquimod, imiquimod TLR8 " TLR9 " CpG, DNA enriched in cytosine:guanosine pairs TLR10 "
References
External links Diagram at scq.ubc.ca