More Enzyme-linked receptors (lect4) Flashcards
What are receptor guanylyl cyclases?
enzyme-linked receptor with extracellular domain and cyclase domain.. these are dimers
How are guanylyl cyclases activated?
natriuretic peptides
what are natriuretic peptides ?
induces natriuresis.. (the discharge of sodium through urine)
give me two types of natriuretic peptides
Atrial natriuretic peptide and Brain natriuretic peptide
Which second messenger is produced upon activation of guanylyl cyclases ?
Cyclic GMP from GTP
does guanylyl cyclase activation involve G-proteins?
NO
What is the Heme binding domain ?
found in intracellular soluble guanylyl cyclases ! not transmembrane
give me an example of a ligand that activates soluble guanylyl cyclases ?
NO which is a gas, cell permeable, short lived hence local signal
what are the two types of guanylyl cyclase ?
membrane associated guanylyl cyclase and soluble guanylyl cyclase
How are cyclic GMP levels reduced ?
by phosphodiesterases + h20 converting it back to GMP
how are the effects of cGMP mediated ?
via protein kinase G which decreases intracellular calcium
how does cGMP activate protein kinase G
cGMP dissociate catalytic subunits from regulatory subunits - regulatory subunits and catalytic subunits are in one polypeptide in protein kinase G
what effect does acetylcholine have on NO conc?
increases it
what effect does acetylcholine have on smooth muscle cell ?
rapid relaxation via soluble guanylyl cyclase which produces cyclic GMP
what is PDE-5 ? what drug inhibits this enzyme ?
viagra … a phosphodiesterase that converts cGMP to 5’ GMP.. hence blocking phosphodiesterase will result in decreased in calcium - therefore leading to smooth muscle relaxation - more blood supply to penis ( erection )
