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:

Types

The following is a list of the five major families of catalytic receptors:

FamilyMemberGeneCatalytic activityEndogenous ligandsSynthetic ligands
ErbErbB1 (epidermal growth factor receptor)tyrosine kinase ECEpidermal growth factor, amphiregulin, betacellulin, epigen, epiregulin, HB-EGF, TGFaGW583340, gefitinib, erlotinib, tyrphostins AG879 and AG1478
ErbB2"
ErbB3"NRG-1, NRG-2GW583340, gefitinib, erlotinib, tyrphostins AG879 and AG1478
ErbB4"Betacellulin, epiregulin, HB-EGF, NRG-1, NRG-2, NRG-3, NRG-4GW583340, 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)NPR1guanylyl cyclase ECAtrial natriuretic peptide
NPR2"C-type natriuretic peptide
NPR3"Atrial natriuretic peptide
NPR4"Uroguanylin
trk neurotrophin receptorTrkAtyrosine kinase ECNerve growth factor > NT-3GW441756, tyrphostin AG879
TrkB"Brain-derived neurotrophic factor, NT-4/NT-5 > NT-3
TrkC"NT-3
p75"NGF, BDNF, NT3, NT4/5
Toll-likeTLR1"
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"

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