Isolation and characterization of glycogen synthase in Dictyostelium discoideum.
We have partially purified the protein and isolated the glcS gene for glycogen synthase in Dictyostelium. glcS mRNA is present throughout development and is the product of a single gene coding for 775 amino acids, with a predicted molecular mass of 87 kD. The sequence is highly similar to glycogen synthase from human muscle, yeast, and rat liver, diverging significantly only at the amino and carboxy termini. Phosphorylation and UDPG binding sites are conserved, with K(m) values for UDPG being comparable to those determined for other organisms, but in vitro phosphorylation failing to convert between the G6P-dependent (D) and -independent (I) forms. Enzyme activity is relatively constant throughout the life cycle: the I form of the enzyme isolates with the soluble fraction in amoebae, switches to the D form, becomes pellet-associated during early development, and finally reverts during late development to the I form, which again localizes to the soluble fraction. Deletion analysis of the promoter reveals a GC-rich element which, when deleted, abolishes expression of glcS.
Williamson
B D
BD
Department of Biology, virginia Polytechnic Institute and State University, Blacksburg 24061-0406, USA.
Favis
R
R
Brickey
D A
DA
Rutherford
C L
CL
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D003001:Cloning, Molecular; D004023:Dictyostelium / Q000201:enzymology* / Q000235:genetics; D018507:Gene Expression Regulation, Developmental; D015971:Gene Expression Regulation, Enzymologic; D017125:Genes, Protozoan / Q000235:genetics; D006006:Glycogen Synthase / Q000737:chemistry / Q000235:genetics* / Q000302:isolation & purification / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008969:Molecular Sequence Data; D008970:Molecular Weight; D010710:Phosphates / Q000494:pharmacology; D010766:Phosphorylation; D011189:Potassium Chloride / Q000494:pharmacology; D017680:Potassium Compounds / Q000494:pharmacology; D011401:Promoter Regions, Genetic / Q000235:genetics; D012333:RNA, Messenger / Q000096:biosynthesis; D016053:RNA, Protozoan / Q000096:biosynthesis; D011993:Recombinant Fusion Proteins; D017384:Sequence Deletion; D017386:Sequence Homology, Amino Acid; D012965:Sodium Chloride / Q000494:pharmacology; D014170:Transformation, Genetic
D010710:Phosphates; D017680:Potassium Compounds; D012333:RNA, Messenger; D016053:RNA, Protozoan; D011993:Recombinant Fusion Proteins; D012965:Sodium Chloride; D011189:Potassium Chloride; C013216:potassium phosphate; D006006:Glycogen Synthase