Biochemistry of Cellular Receptors Flashcards
For each signaling system, give its messenger
nervous system
endocrine system
immune system
NT; hormones; cytokines
The Eicosanoids: Prostaglandins, thromboxjnes and leukotrienes control cellular functions in response to what?
injury
Almost every cell in the body produces Eicosanoids. True or false?
true
Eicosanoids affect what cells?
the cells that produce them or their neighboring cells
What are growth factors
polypeptides that function through stimulation of cellular proliferation e.g EGF, FGF
Define signal transduction
chemical messenger binds to receptor, signal it’s carrying must be converted into an intracellular response
Tyrosine kinase receptors are an example of what type of receptor
enzyme-linked receptor
Jak-Stat receptors are what type of receptor
cytokine receptor
In regards to the ion-channel receptor: Nicotinic acetylcholine receptor, ___ is the NT at neuromuscular junctions
acetylcholine
Nicotinic acetylcholine receptor are found where?
plasma membrane of muscle cells
As acetylcholine binds to the receptor, describe what happens
conformation change opens the narrow portion of the channel (the gate), allowing Na+ to diffuse in and K+ to diffuse out.
Tyrosine Kinase receptors generally exist in the ____ as ___ with a single membrane-spanning helix
membrane; monomers
In regards to the tyrosine kinase receptor, one molecule of ___ generally binds two molecules of the receptor and promotes their ___
GF; dimerization
In regards to the tyrosine kinase receptor, once the receptor dimer has formed, the intracellular tyrosine kinase domains of the receptor ___ each other on certain tyrosine residues
phosphorylate
In regards to the tyrosine kinase receptor, the phosphotyrosine residues form specific binding sites for what?
signal transducer proteins
Serine-Threonine kinase receptors are used by proteins in what superfamily?
transforming growth factor (TGF)
Serine-threonine kinase receptors associate with proteins from the sad family which are ___ ___ transcription actors
gene specific
The superfamily of TGF is involved in what?
tissue repair, immune regulation, and cell proliferation
The Jak-STAT receptor is used by cytokines to regulate what?
proliferation of certain cells
True or false? The Jak-STAT receptor has no intrinsic kinase activity, but it binds the tyrosine kinase Jak
true
STAT is phosphorylated by Jak which causes what?
STAT’s dimerize and move to nucleus where they activate transcription
____ is the guanosine analogue of ATP and is involved in G-protein coupled receptors
GTP
Small G-protiens related to the ___ oncogene are involved in vesicle transport in cells, interactions between the cytoskeleton and cell membrane and cell growth
ras
All the heterotrimeric G protein-coupled receptors are proteins that span the cell membrane ___ times
7
When the signal reaches a G-protein, the protein exchanges GDP for ___
GTP
The resting state of a G-coupled receptor is achieved when GTPase converts GTP to ___
GDP
Messengers that use intracellular receptors must be ___ molecules that are able to diffuse through the plasma membrane
hydrophobic
Lipophilic hormones that use intracellular gene-specific transcription factors include the ____ hormones, ___ hormone, ____ acid and vitamin ___
steroid; thyroid; retinoic; D
In regards to lipophilic hormone receptors, cytosolic (subclass-1) receptors are in the cytosol bound to ___ ___ proteins
heat shock
When a hormone binds to a cytosolic receptor, the heat shock protein is displaced. What happens now?
hormone-receptor complex moves to nucleus and alters transcription
Sex steroids generally fall into the category of ___ receptors
cytosolic
These receptors are a type lipophilic hormone receptors found within the nucleus, not bound to hsps.
Nuclear (subclass-2) receptors
Binding of the hormones to nuclear receptors induces a conformation change (activation). What happens next? Give some examples
transcription is altered; thyroid hormone, retinoids, vitamin-D
Define down-regulation
when a hormone or NT is present in excess, the number of active receptors generally decreases
Define up-regulation
in the presence of a deficiency of the chemical messenger, there is an increase in the number of active receptors
Define internalization
in the case of receptors in the membrane, ligands bind to their receptors, and the ligand-receptor complexes move laterally in the membrane to coated pits, where they are taken into the cell by endocytosis
This is a type of down regulation in which receptors are chemically modified in ways to make them less responsive
desensitization
Ligands that bind to receptors and cause a maximal response are often termed full ____
agonists
Ligands that evoke a sub maximal response, even when filling all the receptors are termed ___ ___
partial agonists
Define antagonist
some ligands bind to receptors with high affinity, yet elicit no response ex: tamoxifen
The affinity of a ligand to the receptor is measured using ___
RRA (radio receptor assay)
____ analysis will give the affinity of a ligand
scatchard
A disease in which antibodies produced attack thyroid stimulating hormone receptors is called what?
grave’s disease
A disease in which antibodies attack nicotinic acetylcholine receptors is called what?
myasthenia gravis
What are the symptoms of myasthenia gravis?
muscle weakness, fatigue
