How would over expression of protein phosphatase 1 affect the
induction of cAMP-inducible genes in response to hormone
stimulation of target cells? Would protein phosphatase 1 affect the
function of cAMP-gated ion channels? Why or why
not?
basically protein phosphatase 1 causes dephosphorylation of
serine residues that are phosphorylayed by protein kinase A(PKA).
PKA has 2 regulatory and @ catalytic subunits, cyclic AMP binds to
the regulatory subunits of PKA to activate them( 4 cyclic AMP
molecules are required to activate 1 pka unit).. catalytic unit
moves to the nucleus and phosphorylates CREB . cyclic AMP inducible
genes are activated by CREB( cAMP response element binding), which
is phosphorylated by PKA. CREB binds to CBP( CREB binding protein)
which then gives response to particular stimulus as it is a
trancription factor. so overexpression of protein phosphatase 1
inhibit the induction of this cascade.
cyclic AMP gated ion channels are opened directly by the binding of
cAMP , not by the phosphorylation so Protein phosphatase 1 has no
effect on the activity of cAMP gated ion channels.
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