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Figure 14: G protein coupled receptors
3) Enzyme linked receptors
They are transmembrane receptors having a catalytic site on the
cytoplasmic domain. When the ligand binds these receptors, they
dimerize, this dimerization activates the receptor’s catalytic site and
results in the enzymatic activity
Example of these receptors: the receptor tyrosine kinase, receptor
serine/threonine kinase, receptor guanylyl cyclase, and receptor tyrosine
phosphatases
Receptor tyrosine and receptor serine and threonine kinases dimerize
when ligand binds to them, then autophosphorylation occurs at the
tyrosine, serine, or threonine sites, respectively. This phosphorylation is
what activates the enzymatic activity of the receptor
Ligands of these receptors may be epidermal growth factor and platelet-
derived growth factor, both binds with receptor tyrosine kinase
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