Chemical messengers Flashcards
receptor on cell is activated by a
ligand
receptors have ____ ____ for ligands to attach to
binding sites
binding of a ligand to a receptor causes a
response, signal transduction, change in the cell
receptors are usually ___ proteins
transmembrane
8 factors that determine the interaction between a ligand and receptor
specificity, affinity, saturation, competition, agonist, antagonist, downregulation, upregulation
specificity
receptor’s ability to bind to a single or very limited type of ligand
high specificity limits ____ with other ____
reactions, ligands
a receptor is like a =
lock
a ligand is like a =
key
(lock and key analogy) : specificity
determines how close a key has to be in order to unlock the lock
affinity
how strongly a receptor binds to a ligand
if a ligand’s affinity to a receptor is strong then their connection will be ___ and can increase more ____ changes
longer, downstream
if a ligand’s affinity to a receptor is weaker then their connection will be ___ and can last for a few ____
shorter, seconds
competition
how effectively other similar compounds may be able to bind to the receptor
example of competition
carbon monoxide competes with O2
agonist
competes with normal chemical messenger, but triggers the same receptor response
an agonist ___ natural ____
enhances, activity
antagonist
competes with ligand, but doesn’t trigger same receptor response
an antagonist blocks
signal transduction
downregulation
decrease in the number of reven
downregulation is usually in response to
an increased concentration of ligands
upregulation
increase in receptors
medications are all about ____
receptors
the binding of a ligand to a receptor causes a ____ change that then leads to ____ activation
conformational, receptor
when the signal transduction pathway is activated, it leads to a
response in the cell
allosteric modulation
affinity of ligand to functional site on a receptor (protein) is dependent on the conformational change of a functional site due to the binding of a modulator protein to a regulator site
functional site
where ligand binds to receptor in order to lead to physiologic processes
the binding of a ligand to a functional site can alter other _____ sites on a multimeric protein
functional
multimeric protein
protein made of multiple subunits with multiple binding/functional sites
example of a receptor being influenced by the bonding of a ligand on a functional site of a multimeric protein
4 sites for O2 to bind to HGB and the first O2 to attach is the hardest, but once it binds the other 3 functional sites for O2 to bind become more cooperative (steeper positive curve)
covalent modulation
the conformational change of a functional site in order to allow a ligand to bond is caused by a chemical reaction, most often phosphorylation
in covalent modulation, there’s a ___ change and changes in _____ distribution
conformational, electrical
most common process used in covalent modulation
phosphorylation
enzyme needed to add a negatively charged phosphate group
protein kinase
phosphorylation
adds a negatively charged phosphate group
what compound is required for phosphorylation, aka what does the protein kinase take a phosphate group from to add it to the charged groups of a receptor protein
ATP
enzyme needed to remove a negatively charged phosphate group
protein phosphatase
properties of lipid soluble messengers
can penetrate phospholipid membranes, receptors usually in nucleus, binding can lead to gene transcription/ protein synthesis or inhibit it
properties of water soluble messengers
cannot penetrate membranes, bind to receptors at cell membrane
examples of water soluble messengers
neurotransmitters, hormones, paracrine agents, autocrine agents
receptor activation done by first messengers (water soluble messengers) can cause
activation of a second messenger in the cell and a cellular response
a receptor acting as an ion channel is activated by a ____ which causes a ____ change that opens an ____
ligand, conformational, ion channel
ions move through an ion channel in the membrane through ____ and an _____ ____
diffusion, electrochemical gradient
the diffusion of ions through an ion channel ___ and ___ of the membrane can trigger some sort of
in, out, a cellular response or interaction
2 examples of what a receptor can act as
ion channel, enzyme
when a receptor acts as an enzyme, the receptor has direct __ activity
protein kinase
if receptors act like an enzyme, they usually have a ___ group
tyrosine
ligand binding to a receptor protein that acts as an enzyme activates its ___ portion
enzymatic
when a receptor tyrosine kinase is activated by a ligand then it ____ itself
autophosphorylates
after auto phosphorylating, the receptor binds to other ___
cytoplasmic proteins
Arachadonic acid is a ___
polyunsaturated fatty acid
arachadonic acid leads to the formation of
eicosanoids
eicosanoids are usually released and act locally, so they act as either ___ or ___ agents
paracrine, autocrine
arachadonic acid is formed by a ___ ____ activating ____ which splits arachadonic acid off of a ____
first messenger, phospholipase A2, phospholipid
what activates the split between arachadonic acid and a phospholipid
phospholipase A2
arachadonic acid can travel down ___ different pathways
2
2 pathways that arachadonic acid can take
cycloogygenase pathway and lipoxygenase pathway
