What are the 4 basic types of receptors?
1. Steroid Receptors — Internal (intracellular) receptors for lipid soluble hormones (steroids & TH) 2. GPLRs (or GPCRs) — Cell surface (transmembrane) receptors linked to G proteins (also called G Protein Coupled Receptors or GPCRs) 3. RTKs — Cell surface (transmembrane) receptors that are — or are linked to — tyrosine kinases. 4. Channels — some transmembrane receptors are ion channels. These will be ignored for now but discussed at length when we get to nerves & muscles. The most famous example is the nicotinic acetyl choline receptor — the receptor involved in nerve-muscle signaling. B. What is special about RTKs? RTK’s are representative of a different type of cell surface receptor involved in signaling. (Different from GPCR’s — see table below for details.) Signal on outside binds to receptor, and activation of proteins, often TF’s, happens inside. Often no second messenger. How does the binding of a ligand on the outside of the cell activate proteins inside? What’s the p
