Ion Channels
used for regulating ion flow into or out of a cell
3 Types of Ion Channels
ungated
voltage-gated
ligand gated
Enzyme-Linked Receptors
participate in cell signalling through extracellular ligand binding and initiation of second messenger cascades
G Protein-Coupled Receptors
have a membrane-bound protein associated with a trimeric G Protein and they initiate second messenger systems