intro to receptors & signal transduction pathway Flashcards
when does a ligand need to bind to an extracellular domain?
charged ligands
what is signal transduction?
the process whereby information (signals) is transmitted to the inside of the cell
what is the process of transduction?
receptor proteins bind “signals” (drugs / endogenous ligands), this causes conformational changes in the structure of the receptor protein then convert the chemical signal into one or more intracellular signal
what can receptors interact with?
drugs and endogenous messenger molecules
give examples of some naturally occuring messengers;:
hormones (insulin, adrenaline), neurotransmitter (acetylcholine), local chemical mediators (histamine, prostaglandins)
what is an antagonist drug?
a type of drug which binds to a receptor but does not alter its activity, it just prevents the agonist from binding/working. could be competitive or non competitive
what is an agonist drug?
a type of drug that binds to and exerts an effect on a receptor, it can activate it. an agonist may be a full agonist or partial
what are the 2 main groups of the receptor proteins?
plasma membrane extracellular transmembrane receptors
cytosolic/nuclear intracellular receptors
how many receptor proteins are there per cell?
between 500 and 100,000
how do hydrophobic drugs pass through the lipid bilayer?
pass through then bind to intracellular receptors
how do hydrophilic drugs pass through the lipid bilayer
bind to plasma membrane extracellular proteins
what are the 3 families of plasma membrane proteins?
ligand-gated ion channels, gpc receptors, tk receptors
what are ligand gated ion channels?
receptors which have an ion channel function
what are gpc receptors?
g-protein coupled receptors is couple to another protein that is capable of binding GTP and GDP
what are TK receptors?
receptors with a catalytic domain capable of phosphorylating tyrosine residues
how many subunits does the nicotinic acetylcholine receptor have?
5 subunits
list some biological functions that GPC receptors mediate:
smell, taste, vision, neurotransmission, hormone secretion, controll of blood pressure, cell growth and differentiation
what do GPC receptors consist of?
a membrane spanning domain consisting of 7 transmembrane helices
what are GPC receptors coupled to?
a GTP protein
how do TK receptors work?
once the cytosolic region of the receptor is activated, it is then capable of phosphorylating to tyrosine residues on other proteins.
what is the only family of cytosolic receptors?
nuclear hormone (Steroid) receptors
how do you characterise a nuclear hormone receptor?
by the presence of a ligand binding domain and a DNA binding domain.
which receptor has an effect on gene expression?
nuclear hormone (Steroid) recpetors
how do nuclear hormone (Steroid) recpetors work?
their ligands exert their effect by causing the receptor to move to the nucleus, where the receptor binds to DNA and acts as a transcriptional regulator, i.e. it has an effect on gene transmission, it either turns gene on or off, most of the time it does this to many genes, not just 1
