Appearance of a nonfunctional isozyme of hepatic glycogen synthase in late gestation.
Glycogen levels, glycogen synthase activities, and glycogen synthase protein levels were determined in liver tissues obtained from 14- to 19-day-old fetal mice, newborn mice, and adult mice. The results of these experiments demonstrate a significant increase in the quantity of hepatic glycogen synthase beginning at Day 17 of gestation and reaching adult levels at birth. However, during the same time period, there is a dramatic decrease in total glycogen synthase activity suggesting that the accumulating glycogen synthase molecules are unable to transfer UDP-glucose to glycogen. These inversely coordinated changes in the quantity and activity of glycogen synthase are consistent with the suggestion that glycogen synthesis in the near-term fetal mouse is being maintained by preexisting enzyme, while accumulating enzyme molecules may represent a quiescent isozyme.
Hsu
S D
SD
Department of Anatomy and Cell Biology, University of Cincinnati, Ohio.
Jaspers
S R
SR
Davis
B B
BB
Cardell
R R
RR
Miller
T B
TB
Drake
R L
RL
D000375:Aging / Q000378:metabolism; D000818:Animals; D005260:Female; D005865:Gestational Age; D006006:Glycogen Synthase / Q000378:metabolism*; D007527:Isoenzymes / Q000378:metabolism*; D008099:Liver / Q000196:embryology / Q000201:enzymology*; D051379:Mice; D008813:Mice, Inbred ICR; D011247:Pregnancy
D007527:Isoenzymes; D006006:Glycogen Synthase