Which is an example of an enzyme-linked receptor?

Which is an example of an enzyme-linked receptor?

• A. Receptor tyrosine kinase
• B. G protein-coupled receptor
• C. Ion channel receptor
• D. Nuclear receptor

Answer: (A)

Enzyme-linked receptors are cell-surface proteins that either have an intrinsic enzymatic domain or recruit one when a ligand binds. The hallmark example is receptor tyrosine kinases: they span the membrane and, upon ligand binding, typically dimerize and autophosphorylate on tyrosine residues. This phosphorylation creates docking sites for downstream signaling proteins, kickstarting cascades such as MAPK or PI3K/Akt that transmit the signal inside the cell. Other receptor types do not rely on an enzyme activity: G protein-coupled receptors activate G proteins to modulate second messengers rather than enzymatically modifying substrates; ion-channel receptors regulate ion flow without enzymatic signaling; nuclear receptors reside inside the cell and act as transcription factors, not membrane-bound enzymes. So the example that fits an enzyme-linked receptor is the receptor tyrosine kinase.

Enzyme-linked receptors are cell-surface proteins that either have an intrinsic enzymatic domain or recruit one when a ligand binds. The hallmark example is receptor tyrosine kinases: they span the membrane and, upon ligand binding, typically dimerize and autophosphorylate on tyrosine residues. This phosphorylation creates docking sites for downstream signaling proteins, kickstarting cascades such as MAPK or PI3K/Akt that transmit the signal inside the cell. Other receptor types do not rely on an enzyme activity: G protein-coupled receptors activate G proteins to modulate second messengers rather than enzymatically modifying substrates; ion-channel receptors regulate ion flow without enzymatic signaling; nuclear receptors reside inside the cell and act as transcription factors, not membrane-bound enzymes. So the example that fits an enzyme-linked receptor is the receptor tyrosine kinase.