Potato Tuber UDP-Glucose:Protein Transglucosylase Catalyzes Its Own Glucosylation
1Instituto de Investigaciones Bioquimicas "Fundación Campomar," Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Patricias Argentinas 435, (1405) Buenos Aires, Argentina.
Abstract:
Potato (Solanum tuberosum L.) tuber UDP-glucose:protein transglucosylase (UPTG) (EC 2.4.1.112) is involved in the first of a two-step mechanism proposed for protein-bound alpha-glucan synthesis by catalyzing the covalent attachment of a single glucose residue to an acceptor protein. The resulting glucosylated 38-kilodalton polypeptide would then serve as a primer for enzymic glucan chain elongation during the second step. In the present report, we describe the fast protein liquid chromatography purification of UPTG from a membrane pellet of potato tuber. An apparently close association of UPTG, phosphorylase, and starch synthase was observed under native conditions during different purification steps. Enrichment of a 38-kilodalton polypeptide was found throughout enzyme purification. It is now shown that the purified UPTG, with an apparent molecular mass of 38 kilodaltons, undergoes self-glucosylation in a UDP-glucose- and Mn(2+)-dependent reaction. Therefore, it is concluded that UPTG is the enzyme and at the same time the priming protein required for the biogenesis of protein-bound alpha-glucan in potato tuber.
More Related Videos
Related Concept Videos
Biosynthesis of Polysaccharides
Protein Folding Quality Check in the RER
Oligosaccharide Assembly
Multiple sugar molecules that may or may...
Glucose Transporters
Facilitated diffusion-glucose transporters (GLUTs) are encoded by the solute-linked carrier (SLC) family 2, subfamily A gene family, or SLC2A. The 14 GLUT protein members are distributed into three classes:
Overview of Carbohydrate Metabolism
Glucose transport into cells is facilitated by a family of transport proteins called GLUT (Glucose Transporters). GLUT4 is the primary glucose transporter for insulin-stimulated glucose...
Phase II Reactions: Glucuronidation


