BIO230H1 Lecture Notes - Lecture 8: Adenylyl Cyclase, Electrochemical Gradient, Nitric Oxide Synthase
BIO230
Lecture 8
Receptors
!
Nitric&oxide&(NO)&–&a"very"small"signalling"molecule"made"by"deamination"of"arginine"by"
NO"synthase."Acts"locally,"has"a"very"short"half-life."Affect"smooth"muscles"and"other"target"
cells.""
NO&synthase&–"an"anzyme"which"produces"and"which"gets"activated"in"endothelial*cells"via"
teh"action"of"acetylcholine.""
Nitroglycerine&–"a"drug,"which"is"used"to"treat"pain."It"is"converted"to"NO"and"relaxes"blood"
vessels,"reducing"workload"of"the"heart.""
"
Small*hydrophobic*signalling*molecules:*
1) Steroid"hormones;"
2) Thyroid"hormones;"
3) Retinoids&–"small"signalling"molecules"produced"from"Vitamin*A,"which"regulate"the"
development;&
4) Vitamin"D;"
"
Nuclear&receptors&-"receptors"which"contains"binding"sites"for"a"small"hydrophobic"
molecules"and"for"DNA."
"
Orphan&nuclear&receptors&–"nuclear"receptors"which"ligands"are"unknown.""
"
Ion&channels:&1)"voltage-gated;"
&&&&&&&&&&&&&&&&&&&&&&&&&&&&&2)"ligand-gated"(extracellular);"
"""""""""""""""""""""""""""""3)"ligand-gated"(intracellular);"
"""""""""""""""""""""""""""""4)"mechanically"gated;"
"
Electrochemical gradient is a gradient of electrochemical potential, usually for an ion that can
move across a membrane. The gradient consists of two parts, the electrical potential and a
difference in the chemical concentration across a membrane.
"
G-protein&coupled&receptors&(GPCRs)&–"7-pass"transmembrane"proteins"that"are"coupled"
to"G-protein"(GTP-bidning"protein"which"contains"3"subunits – α, β, γ) and are activated by
proteins, small molecules and light.
Guanine exchange factor (GEF) – factor (a protein) that exchanges GDP to GTP (in relation to
GPCRs, that happens on α-subunits). Activated GPCR acts as a GEF.
Regulator of G protein signaling (RGS) – protein that turns off the activity of GPCR by
exchanging GTP to GDP (acting as GTPase activating protein – GAP)
Adenylyl&cyclase&–"an"enzyme"which"synthsizes"cAMP"from"ATP."
cAMP&phosphodiesterase"–"an"enzyme"which"destroys"cAMP.""
"
Protein kinase A (PKA) is a family of enzymes whose activity is dependent on cellular levels
of cyclic AMP (cAMP). PKA is also known as cAMP-dependent protein kinase. Protein
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BIO230H1 Full Course Notes
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