intro to receptors & signal transduction pathway

Question 1

when does a ligand need to bind to an extracellular domain?

Answer 1

charged ligands

Question 2

what is signal transduction?

Answer 2

the process whereby information (signals) is transmitted to the inside of the cell

Question 3

what is the process of transduction?

Answer 3

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

Question 4

what can receptors interact with?

Answer 4

drugs and endogenous messenger molecules

Question 5

give examples of some naturally occuring messengers;:

Answer 5

hormones (insulin, adrenaline), neurotransmitter (acetylcholine), local chemical mediators (histamine, prostaglandins)

Question 6

what is an antagonist drug?

Answer 6

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

Question 7

what is an agonist drug?

Answer 7

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

Question 8

what are the 2 main groups of the receptor proteins?

Answer 8

plasma membrane extracellular transmembrane receptors

cytosolic/nuclear intracellular receptors

Question 9

how many receptor proteins are there per cell?

Answer 9

between 500 and 100,000

Question 10

how do hydrophobic drugs pass through the lipid bilayer?

Answer 10

pass through then bind to intracellular receptors

Question 11

how do hydrophilic drugs pass through the lipid bilayer

Answer 11

bind to plasma membrane extracellular proteins

Question 12

what are the 3 families of plasma membrane proteins?

Answer 12

ligand-gated ion channels, gpc receptors, tk receptors

Question 13

what are ligand gated ion channels?

Answer 13

receptors which have an ion channel function

Question 14

what are gpc receptors?

Answer 14

g-protein coupled receptors is couple to another protein that is capable of binding GTP and GDP

Question 15

what are TK receptors?

Answer 15

receptors with a catalytic domain capable of phosphorylating tyrosine residues

Question 16

how many subunits does the nicotinic acetylcholine receptor have?

Answer 16

5 subunits

Question 17

list some biological functions that GPC receptors mediate:

Answer 17

smell, taste, vision, neurotransmission, hormone secretion, controll of blood pressure, cell growth and differentiation

Question 18

what do GPC receptors consist of?

Answer 18

a membrane spanning domain consisting of 7 transmembrane helices

Question 19

what are GPC receptors coupled to?

Answer 19

a GTP protein

Question 20

how do TK receptors work?

Answer 20

once the cytosolic region of the receptor is activated, it is then capable of phosphorylating to tyrosine residues on other proteins.

Question 21

what is the only family of cytosolic receptors?

Answer 21

nuclear hormone (Steroid) receptors

Question 22

how do you characterise a nuclear hormone receptor?

Answer 22

by the presence of a ligand binding domain and a DNA binding domain.

Question 23

which receptor has an effect on gene expression?

Answer 23

nuclear hormone (Steroid) recpetors

Question 24

how do nuclear hormone (Steroid) recpetors work?

Answer 24

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