BI110 Lecture Notes - Lecture 19: Integral Membrane Protein, Signal Transduction, Conformational Change
Document Summary
Cell surface receptors: gated ion channels: both a transporter and a receptor. Transports ions; in the absence of its signal (ligand), the gate is closed. Binding of ligand allows gates to open and ion flow begins, transport into the cell occurs. Low affinity, ligands can be released from the channel. Concentration of the signal determines how quickly the cycle occurs. Ligand binds to receptor domain, causes conformational changes in the protein, specifically to the enzymatic domain inside the cell. Receptor dimerization occurs, and there is cross phosphorylation that activates the proteins and recruits other enzymes that are attracted to the phosphorylated receptors. Signal transduction causes a cellular response after other proteins have been recruited: g-protein coupled receptors: very widespread. The receptor is an integral membrane protein. Coupled to another protein (g as in gtp or gdp). When epinephrine is absent, the g protein coupled to the receptor and bound to gdp (the inactive state of the receptor).
