Bartling Guide Flashcards
cellular signal transducttion cassettes detect, amplify and
integrate external signals
cellular signal transduction cassettes are compromised of
- specific cell surface membrane receptors
- effector signalling elements
- regulatory proteins
Six steps of signalling
- synthesis
- release
- transport
- binding
- change
- removal/termination
- degradation
1st step of signaling
synthesis of signaling molecule
2nd step of signaling
release of signaling molecule
3rd step of signaling
transport of signaling molecule to target cell
4th step of signaling
binding of the ligand by a specific receptor protein and change in comformation
5th step of signaling
change in cellular metabolism, function or development (cellular response)
6th step of signaling
removal of ligand, terminating cellular response
7th step of signaling
degradation of ligand
chemical messengers are made by
endocribe cells
chemical messengers are secreted into
the blood stream
chemical messengers
affect gene expression and protein synthesis
autocrine acts on
same cell that secreted them
paracrine acts on
other cells
types of hormones
- steroids
- amine
- peptide
- polypeptide
cholesterol is a
steroid hormone
cholesterol precursor
- corticosteroids
- androgens
- estrogens
steroid hormones immediately diffuse out of _____ and into _____
out of endocrine cells and into blood stream
steroids are _____ solubule
lipid soluble
steroids can/cant cross cell membrane
can
intracellular (cytoplasmic) receptors located where?
inside trget cells
steroid hormones have a _____ half life/ ____ acting than peptide hormones
longer/slower
amine hormones are derived from
tyrosine or tryptophan
amine hormones are stored in______ until secreted
endocrine cells until secreted
receptors of amine hormones can be located
on cell surface of intracellular
polypeptide hormones are_____ soluble
water soluble
polypeptides do or do not pass through cell membrane
do not
polypeptide hormones are termed
first messengers as they bind to external receptors
second messengers are
internal reactions
2 low molecular weight signalling molecules
cAMP or calcium
intracellular effects are mediated by
second messengers
g protein coupled receptors are
integral membrane proteins (extracellular N terminus)
g protein coupled receptors have seven
transmembrane spanning a- helices
g protein coupled receptors have three
extracellular and intracellular loops
third intracelluular loop recruits
g proteins
g proteins have intracellular ______ tail membrane
c- terminal tail membrane
g protein has no
intrinsic catalytic domains
g protein activates
adenylyl cyclase
adenylyl cyclase
converts ATP to cAMP
G protein also activates
protein kinases in the cytosol
phosphodiesteras inactivates
cAMP (turns off cell response)
specificity of g protein conferred by
alpha subunit (which ocntains the GTP binding site and an intrinsic GTPase activity)
adenylyl cyclase
activated by alpha subunit of G protein
each bound hormone can stimulate
many G alpha subunits that amplifies original hormone signal
bacterial toxins that target g proteins
cholera toxin and pertussis toxin
cholera toxin
increase in cAMP within intestinal epithelial cells which leads to phosphorylation of Cl- channels and efflux of electrolytes and water
cholera toxin results in severe
diarrhea
pertussis toxin also called
whooping cough
pertussis toxin enhances
cAMP levels that inhibits neutrophil functions
tyrosine kinase linked receptors have no intrinsic
enzymatic activity
ligand bonding in tyrosine kinase receptors forms a dimer that activates
tyrosine kinases that phosphorylate downstream targets (signal cascade)
