1 L3 Cell Signalling Pathways 1 Flashcards
Are steroids lipid soluble or water soluble
Lipid soluble- derived from cholesterol
Cortisol- Where is it produced and what is it’s function
Adrenal gland- released in response to stress
Aldosterone- Where is it produced and what is it’s function
Adrenal cortex- Released in response to blood pressure drop
Progesterone, Estradiol, Testosterone- Where are they produced and what are their functions
Gonads- Sex hormones that have multiple roles
Neurosteroids- Where are they produced and what are their functions
Neurons and Glial cells- have many functions within brain
Describe how intracellular receptors alter gene expression (starting from ligand binding)
Ligand binds and changes receptor shape - If in cytpolasm, the receptor-ligand complex enters the nucleus - The change in shape reveals a region that will specifically bind DNA by “activating” it
What does aldosterone do
Helps retain water in blood and therefore blood volume by facilitating sodium reabsorption in the nephron
Where is the receptor for aldosterone located
Cytoplasm
How does aldosterone alter gene expression
By up-regulating synthesis of proteins that regulate sodium/water reabsorption e.g. Na/K pump
True or False- Thyroid hormone (lipophilic) can cross the cell membrane. Explain reasoning
False- it cannot cross membrane because iodine gives it a negative charge. It enters through transport channels in membrane instead
Where is the receptor for thyroid hormone locates
Inside nucleus- bound to DNA response element
What does thyroid hormone do
Helps with metabolism, bone growth, protein synthesis etc
How does thyroid hormone alter gene expression
The receptor inhibits gene expression when inactive. When TH binds it activates the receptor and therefore initiates gene transcription
Are GPCR integral or peripheral
Integral
How many (pass) transmembrane domain receptors (TM) and what are they coupled to
7 (7TM)- coupled to G proteins
What are the 3 subunits of G proteins
Alpha, Beta, Gamma
What are the 3 classes of G proteins
Stimulatory, Inhibitory, Activating phospholipase
Of the 6 classes of GPCR, which is the most common
1 or A
What are 4 GPCR ligands
Pheromones, Hormones, Odors, Neurotransmitters
Describe the mechanism of GPCR action
Ligand binds and causes conformational change to GPCR - Gives GPCR ability to act as (GEF) guanine nucleotide exchange factor - G protein activated by exchanging GDP for GTP - Alpha unit (bound to GTP) dissociates from Beta and Gamma subunits - Initiates signalling cascade
What are the 2 main transduction pathways that GPCRs use
cAMP (cyclic AMP)
PLC (phospholipase C)
