9.3 cell-surface and intracellular receptors Flashcards
what is a ligand?
a signalling molecule
what is a ligand bonding site?
a location on the receptor to which ligands bond
what causes a conformational change in the receptor?
a ligand binding to a ligand-binding site. “activates the receptor”
characteristics of the bond when signalling
the bond is non-covalent and highly specific, ligand only binds to a receptor with a specific ligand bonding site.
the location of a receptor depends on
whether the signalling cell is polar or non polar
What occurs during polar signalling?
polar signalling molecules cannot cross the plasma membrane and rely on cell surface receptors. when the signal binds to the ligand bonding site in the extracellular domain of the receptor, it undergoes a conformational change which activates the molecule. the receptor acts as a bridge between the hydrophilic signal and the hydrophobic core of the plasma membrane
what occurs during non polar signalling?
small non polar signalling molecules can freely pass through the plasma membrane and activate cytoplasmic receptors. since these signals such as steroids are hydrophobic then can easily enter the cell. the steroid hormone bind to a receptor protein in the cytosol or in nucleus to form receptor-steroid complexes and overall end up in the nucleus to where they act as a control expression for genes.
What are the 3 types of cell- surface receptors?
- G protein- coupled receptors
- receptor kinases
- ion channels
what are the two types of intracellular receptors
- in the cytosol -> nucleus
2. in nucleus
What is G protein- coupled receptor?
a receptor that couples to G proteins, which bind to guanine nucleotides GTP and GDP
What is receptor kinase?
a receptor that is an enzyme that adds a phosphate group to another molecule
what is a ligand- gated ion channel?
a receptor that alters the flow of ions across the plasma membrane when bound by its ligand.
what is phosphorylation and dephosphorylation?
when a kinase transfers a phosphate group from ATP to a protein activating the protein, or a phosphatase removes a phosphate group from the protein deactivating it.
how do ion channels open?
in response to changes in voltage across the plasma membrane or when bound by their ligand
What happens after a signalling molecule binds to its receptor and flips a molecular switch in ion channel signalling?
following receptor activation, a signal is sent to target the interior of the cell, the cell responds then is terminated.
