UDP-( sup 14 C)glucose-labelable polypeptides from pea: Possible components of glucan synthase I activity

Journal Article · Sat Apr 01 04:00:00 EST 1989 · Plant Physiology, Supplement; (USA)

OSTI ID:6610847

Ray, P M; Dhugga, K S; Gallaghar, S R ^[1]

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1. Stanford Univ., CA (USA)

A membrane-bound polypeptide doublet of about 40 kD can be rapidly labeled with UDP-({sup 14}C)glucose under the assay conditions for glucan synthase I (GS-I). Label seems covalently bound, and chases when unlabeled UDPG is added; it might represent a covalent intermediate in polysaccharide synthesis. Labeling and GS-I activity show several common features: they co-sediment with Golgi membranes in sucrose gradients; they depend similarly on Mg{sup 2+} or Mn{sup 2+} (not Ca{sup 2+}); they decrease dramatically from stem apex to base, and are higher in epidermis than internal tissue; they show similar sensitivities to several inhibitors. But the doublet still labels after polysaccharide-synthesizing activity has been destroyed by Triton X-100. The doublet polypeptides might be glucosyl tranferases whose ability to transfer glucose units to a glucan chain is detergent-sensitive, but to accept glucose from UDPG is not; or they might be detergent-insensitive primary glucose acceptors, from which a distinct, detergent-sensitive transferase(s) move(s) these units to glucan chains.

• OSTI ID: 6610847
• Journal Information: Plant Physiology, Supplement; (USA), Journal Name: Plant Physiology, Supplement; (USA) Vol. 89:4; ISSN PPYSA; ISSN 0079-2241
• Country of Publication: United States
• Language: English

Related Subjects

550201* -- Biochemistry-- Tracer Techniques
59 BASIC BIOLOGICAL SCIENCES
ALDEHYDES
CARBOHYDRATES
CARBON 14 COMPOUNDS
CELL CONSTITUENTS
CELL MEMBRANES
ENZYME ACTIVITY
ENZYMES
GLUCOSE
HEXOSES
ISOTOPE APPLICATIONS
LABELLED COMPOUNDS
LABELLING
MEMBRANE PROTEINS
MEMBRANES
MONOSACCHARIDES
ORGANIC COMPOUNDS
PEPTIDES
POLYPEPTIDES
PROTEINS
SACCHARIDES
TRACER TECHNIQUES
TRANSFERASES