Plant polypeptides reversibly glycosylated by UDP-glucose. Possible components of Golgi beta-glucan synthase in pea cells.
In pea membranes, UDP[14C]Glc glycosylates a approximately 40-kDa polypeptide doublet. This label rapidly disappears if excess unlabeled UDP-Glc, or UDP, is added, indicating that the glycosylation is reversible, and suggesting that the glycosylated polypeptides might be intermediates in a glycosyl transfer reaction. Glycosylation of the doublet requires a divalent cation, the effective ions being the same (except for Zn2+) as those that activate Golgi-localized beta-glucan synthase (GS-I) activity. Treatments that inhibit GS-I also inhibit doublet glycosylation. The doublet is associated with Golgi (and to a minor extent with plasma) membranes and occurs also in the soluble fraction. The Golgi-bound doublet may be a component of the GS-I system. Immunological, inactivation, and fractionation evidence indicates that at least one other polypeptide is required in GS-I activity.
Dhugga
K S
KS
Department of Biological Sciences, Stanford University, California 94305.
Ulvskov
P
P
Gallagher
S R
SR
Ray
P M
PM
D002458:Cell Fractionation; D002462:Cell Membrane / Q000378:metabolism; D002736:Chloroplasts / Q000378:metabolism*; D007887:Fabaceae / Q000378:metabolism*; D005964:Glucosyltransferases / Q000378:metabolism*; D006031:Glycosylation; D006056:Golgi Apparatus / Q000201:enzymology*; D007425:Intracellular Membranes / Q000378:metabolism*; D007700:Kinetics; D008565:Membrane Proteins / Q000302:isolation & purification / Q000378:metabolism*; D008970:Molecular Weight; D010940:Plant Proteins / Q000302:isolation & purification / Q000378:metabolism*; D010946:Plants, Medicinal; D014532:Uridine Diphosphate Glucose / Q000378:metabolism*
D008565:Membrane Proteins; D010940:Plant Proteins; C036655:1,3-alpha-D-glucan synthase; D005964:Glucosyltransferases; D014532:Uridine Diphosphate Glucose