CEP Flashcards
(259 cards)
Endocrine signalling
Secreting hormone into blood to reach target cell
Paracrine signalling
Hormones secreted to reach nearby cells
Autocrine signalling
Hormones to a local effect (target sites on the same cell)
How is the response to a drug/hormone measured?
Radio ligand binding assay
Amount of radioactivity is proportional to number of receptors
EC50
Effective concentration 50%
The concentration required to make 50% response (effect)
Kd (dissociation constant)
50% of receptors occupied (binding)
Affinity equation
1/Kd (low Kd = high affinity)
Why measure ligand binding?
To see affinity of drug
Endocrinology
The study of hormones
What are the four types of hormone?
Protein (insulin)
Steroid (cholesterol)
Amine/small peptide (tyrosine)
Amino acid derivatives
How are hormones measured?
Bioassays
Immunoassays
Mass spectrometry
What are the anterior pituitary hormones?
ACTH
TSH
GH
LH/FSH
PRL
What are the posterior pituitary hormones?
Vasopressin
Oxytocin
How to treat underactive glands?
Hormone replacement
Can be due to autoimmune
Primary/secondary can effect later on down the line and not appear until then
How to treat over active glands?
Block receptors
Often caused by tumours (surgery)
What are the 4 main types of receptors?
Ligand-gated ion channels (ionotropic)
G-proteins coupled receptors
Kinase-linked receptors
Nuclear receptors (not on plasma membrane)
What is the mechanism of ionotropic/ligand-gated ion channels?
Ion channels open when ligand binds
Causes change in membrane potential as +/- ve charges change
Can cause depolarisation/hyperpolarisation
What is the mechanism of GPCRs?
Ligand binds
G protein activates/changes conformation
Has a postage or negative effect
Causes ions channels to open or enzymes to produce second messenger
Resulting in a signalling cascade
What is the mechanism of kinase-linked receptors?
Ligand bonds directly to enzyme
Conformation change
Phosphorylation cascade occurs
Gene transcription
Protein synthesis
What is the mechanism of nuclear receptors?
Ligand diffuses directly across the membrane
Binds in nucleus to transcriptional factor
Gene transcription
Protein synthesis
What is the fastest receptor?
Fastest: l-g ion channels
GPCRs
Kinase-linked receptors
Nuclear receptors
How does Adenylyl cyclase work?
AC is an effector enzyme activated by a g-protein
It converts ATP into cyclic AMP which is a second messenger
Signal is stopped by cAMP phosphodiesterase
How does phospholipase C work?
It has 2 second messengers
Gq activates PLC
Causes PIP2 to convert to DAG and InsP3
Causes Ca2+ to be released from ER
What does a protein kinase do?
Adds phosphate