BIOSC 0715 Lecture Notes - Lecture 12: Cell Surface Receptor, Autocrine Signalling, Paracrine Signalling
Document Summary
Trying to maintain homeostasis: gap junctions in animal cells, plasmodesmata in plant cells. Paracrine signaling close-by: neuronal response neurotransmitter stimulates target cell. Components of cell signaling: reception, transduction, response, termination. Two types of signal molecules: hydrophobic signal enters cell, goes straight to target (receptor in cytoplasm or nucleus, hydrophilic signal never enters cell, binds to plasma membrane receptor that initiated message to inside of cell. Ligands non-covalent: charge interactions, hydrophobic/hydrophilic, temporary/reversible. Ion channel: cell surface receptor particular to hydrophilic ligands, ex. Acetylcholine opens ion channels: acetylcholinesterase breaks down acetylcholine to shut off receptor, maintains a finite period of stimulation. Intracellular: membrane soluble (lipid-like/steroid) molecules pass through plasma membrane, receptor in cytosol, both pass together through nuclear pores, alters protein synthesis. Second messengers: atp camp, adenylate/adenylyl cyclase activated by g-protein, creates camp from atp, epinephrine uses camp, which starts a phosphorylation cascade, ex.