Membrane Bound Reception:

• Hydrophilic ligand binds to a receptor that is embedded in the cell membrane

  • Does NOT CROSS the membrane

• Signal is amplified and moved from the membrane to the nucleus via a transduction pathway

• Most common method

Intracellular Receptors

• In the cell

• Lipid soluble ligands diffuse across the membrane and bind to the receptor inside the cell

• This complex travels directly to the nucleus to initiate cell response, bypassing transduction

Signal Transduction

• Membrane bound receptors require use of transduction to move the signal from the membrane to the nucleus

• Ligand binds to the receptor causing it to change shape

  • Trasnmits signal into cell

• Second messenger (like cyclic AMP) is activated and phosphorylates the next protein in the chain to activate it

• Occurs over and over until the last protein in the pathway (usually a transcription factor) enters the nucleus and initiates the cell response