Kinetic and immunologic evidence for the absence of glucose-6-phosphatase in early human chorionic villi and term placenta

Varda Barash, Aryeh Riskin, Eleazar Shafrir, Ian D. Waddell, Ann Burchell

Research output: Contribution to journalArticlepeer-review

Abstract

The existence of the enzyme glucose-6-phosphatase (G6Pase) in early and term human placenta was investigated by comparing the characteristics of placental microsomal glucose 6-phosphate (G6 P) hydrolytic activity and liver G6Pase. Placental microsomes exhibited similar apparent Km values for G6 P and β-glycerophosphate in intact and deoxycholate-treated microsomes, heat stability at acidic pH, low latency of mannose 6-phosphate hydrolysis, very low activity of pyrophosphate:glucose phosphotransferase, and undetectable [U-14C]G6 P transport into the placental microsomes, all of which indicated that specific G6Pase activity does not exist in placenta. Immunological evidence of the absence of both 36.5 kDa and T2 proteins, which represent the G6Pase catalytic protein and the phosphate / pyrophosphate transporter protein, respectively, confirmed that early and term human placenta are devoid of the multicomponent G6Pase enzyme.

Original languageEnglish
Pages (from-to)161-167
Number of pages7
JournalBiochimica et Biophysica Acta - General Subjects
Volume1073
Issue number1
DOIs
StatePublished - 23 Jan 1991
Externally publishedYes

Keywords

  • (Human placenta)
  • Chorionic villi
  • Glucose-6-phosphatase
  • Microsome

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