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Chemical Messengers
areas of interaction
cell surface receptors / external receptors
most in cell membrane
integral proteins
internal receptors
most in cytoplasm or nucleus
entering chemicals must be hydrophobic and like lipids)
examples
steroids
thyroid hormones (T3 T4)
vitamin E, A, D and K (fat soluble)
affects DNA
receptors
ligands
hormones
neurotransmitter
like a key matching a receptor
only from body, not drugs
messenger that carries information to cell with appropriate receptor
binds to internal or external receptor
membrane receptors
integral proteins
single protein can span the membrane
penetrate through multiple times
most commonly 7 times
most commonly alpha helix shape
ligand related types
ligand gated ion channels
chemicals outside cell
GABA
actytolecholine
glycin
seratonin
ATP
cGMP
cAMP
Ca
IP3
usually passing Na, K, Ca, or Cl
receptors coupled to G protein / G protein associated
single chain passing 7 times through membrane
G receptor inside
examples
epinephrine
oxytocin
norepinephrine
G-Proteins
have 3 units
alpha
beta
gama
in resting state alpha hooked to GDP
after reception of ligand, GDP switches for GTP and alpha is broken off with it
alpha-GTP unit then interacts with a molecule downstream on the membrane
example 1
downstream AC (adenylyl cyclase)) molecule then when hit + ATP results in cAMP (enzymatic action)
cAMP than affects/activates PK (protein kinase)-> PKp and/or phosphotase
GP (Glycogen phosphorylase) + PKp = GPp
GPp causes glycogen break down to release glucose
also PK -> GS (glycogen synthase) to become GSp to stop glycogen production
example 2
alpha-GTP hits PL (phospholipase) and it releases IP3 or Arachidonic Acid
IP3 then reacts with another receptor
affects Ca release to activate cell function
PIP2 activated by PL ->Â IP3 (idenosin triphosphate) (leaves membrane) and DAG (stays in membrane)
IP3 goes to ER to open calcium channels for release
Phospholipids activated by PL -> Arachidonic Acid
goes to
cycloxygenase (COX)
Prostoglandins
aspirin stops COX -> Prostoglandins
5-Lipoxygenase (LOX)
Leukotrienes
both create the inflamatory response
cortisol inhibits creation of AA
catalytic receptors
cross membrane once
act as enzymes - causing a reaction
example
cytokine receptors
receptor receives ligand
Product released from associated protein (like PLC)
intracellular receptors
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