Topography and function of Golgi uridine-5'-diphosphatase from pea stems

Ariel Orellana, Guy Neckelmann, Lorena Norambuena

Research output: Contribution to journalArticlepeer-review

20 Citations (Scopus)

Abstract

Golgi UDPase is an enzyme that has been shown to function in polysaccharide biosynthesis, but its role in this process is not yet clear. In this study we identified Golgi UDPase activity in pea (Pisum sativum) stems and differentiated it from another UDPase activity. We demonstrated that Golgi UDPase is an integral membrane protein, based on specific partitioning of this activity into Triton X-114. Analysis of its topology using sealed, right-side-out Golgi vesicles and treatment with proteinase K suggested that its active site faces the Golgi lumen. Studies aimed at understanding the function of Golgi UDPase by incubating Golgi vesicles with [β-32P]UDP-glucose (Glc) to generate [β-32P]UDP upon Glc transfer in situ showed that 32P(i), but not [β-32P]UDP, was formed, suggesting that UDPase quickly hydrolyzed the UDP formed during Glc polymerization. We found that the Golgi UDPase was highly active in the elongating region of the third internode, whereas no activity was detected in the first and second internodes of etiolated pea seedlings. These results suggest that UDPase removes the UDP formed during Glc polymerization and could be important in the mechanism of polysaccharide biosynthesis.

Original languageEnglish
Pages (from-to)99-107
Number of pages9
JournalPlant Physiology
Volume114
Issue number1
DOIs
Publication statusPublished - 1997

ASJC Scopus subject areas

  • Physiology
  • Genetics
  • Plant Science

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