Glycogen synthesis in the obliquely striated muscle of Ascaris suum.
A glycogen synthase, designated GS II, which occurs in a protein/carbohydrate complex has been purified from Ascaris suum muscle. The purified GS-II complex which is eluted from concanavalin-A--Sepharose contains proteins with Mr 140,000 and 66,000 and a glycoprotein with a carbohydrate/protein mass ratio of 3:1. GS II activity was totally dependent on glucose 6-phosphate, but exogenous glycogen was not required for polysaccharide synthesis. The GS-II complex was not phosphorylated by cyclic-AMP-dependent protein kinase, and antibodies to the protein and carbohydrate components of GS II did not cross react with the purified cyclic-AMP-regulated glycogen synthase (GS I) from A. suum muscle. Polysaccharide which was synthesized de novo by the complex was added to the large-molecular-mass glycoprotein in GS II. The glycogen-like character of the newly synthesized polysaccharide was confirmed by the observation that glycogen phosphorylase utilized the polymer as substrate in both the synthesis and degradation reactions. A model is discussed in which a core glycoprotein serves as the substrate for a glycogen synthase which is distinctly different from GS I.
Ghosh
P
P
Department of Biological Sciences, University of North Texas, Denton 76203.
Heath
A C
AC
Donahue
M J
MJ
Masaracchia
R A
RA
D000818:Animals; D001200:Ascaris / Q000201:enzymology*; D002848:Chromatography, DEAE-Cellulose; D002850:Chromatography, Gel; D006003:Glycogen / Q000096:biosynthesis*; D006006:Glycogen Synthase / Q000302:isolation & purification / Q000378:metabolism*; D007700:Kinetics; D008970:Molecular Weight; D009132:Muscles / Q000201:enzymology*; D010763:Phosphorylase b / Q000378:metabolism
D006003:Glycogen; D010763:Phosphorylase b; D006006:Glycogen Synthase