PHSL233 Lecture Notes - Phosphodiesterase, Exocytosis, Gtpase
24 Jul 2013
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Document Summary
When signalling molecules are sent out into the bloodstream, most cells will have contact with this signalling molecule. But only cells with the correct receptor can respond to this signal (ligand). So when ligand binds to receptor, this causes an activation of a effector which often is a enzyme. Different cellular response could be present for the same ligand depending on the cell. Ligands can be water or lipid soluble, water solubles such as peptide hormones cannot penetrate the plasma membrane so they bind to their receptor outside the membrane, usually an integral membrane protein. Lipid soluble such as steroid and thyroid hormones can diffuse through the plasma membrane so they bind their receptor in the cytoplasm of cell. Also a negative feedback is present some way along the pathway where it will act to decreae the signal and turn off the cellular response.
