chapter 25 Flashcards
what is the monomer that is used to extend the glycogen chain
UDP-glucose
what is the glucose donor in glycogen synthesis
UDP-glucose
what synthesizes UDP-glucose
UDP-glucose pyrophosphorylase
is the hydrolysis of pyrophosphate reversible
no
UDP-glucose is an activated form of
glucose
what is the key regulatory enzyme in glycogen synthesis
glycogen synthase
what does glycogen synthase do
transfers a glucose moiety from UDP-glucose to the C-4 terminal residue of a glycogen chain to form a-1,4-glycosidic bond
how many ATP molecules are required in order to incorporate dietary glucose into glycogen
2
glycogen synthase requires what as a primer
polysaccharide of glucose residues
what synthesizes the primer
glycogenin
glycogen synthase is usually inactive when
in the phosphorylated b form
glycogen synthase is usually active when
in the unphosphorylated a form
glycogen synthesis is inhibited by
the same glucagon and epinephrine signaling pathways that stimulate glycogen breakdown
what does protein phosphatase (PP1) do
shifts glycogen metabolism from the degradation mode to the synthesis mode
how to PP1 work
removes phosphoryl groups from glycogen synthase b, converting it to the more active a form
also removes phosphoryl groups from phosphorylase kinase and glycogen phosphorylase, inhibiting glucose degradation
