These tools will no longer be maintained as of December 31, 2024. Archived website can be found here. PubMed4Hh GitHub repository can be found here. Contact NLM Customer Service if you have questions.


Pubmed for Handhelds

PUBMED FOR HANDHELDS

Search MEDLINE/PubMed

  • Title: Investigations on the possible involvement of phospholipids in the glucose-6-phosphate transport system of rat-liver microsomal glucose-6-phosphatase.
    Author: Schulze HU, Speth M.
    Journal: Eur J Biochem; 1980 May; 106(2):505-14. PubMed ID: 6249579.
    Abstract:
    Interrelationships between the catalytic behavior of glucose-6-phosphatase and the structure of rat-liver microsomal membranes were investigated. 2. Rabbit anti-microsomal serum completely inhibited glucose-6-phosphate hydrolysis in detergent-modified microsomes but showed no inhibitory effect on the enzyme activity of intact or mechanically disrupted vesicles. 2. Controlled proteolysis of intact microsomes using carboxypeptidase A and/or aminopeptidase M largely denatured enzymes situated on the outer surface of the microsomal vesicles such as monodehydroascorbate reductase and cytochrome c reductase. However, it did not affect the glucose-6-phosphatase activity at all, which remained in a latent state within the membrane. 3. Temperature studies on glucose-6-phosphatase have revealed that only the enzyme activity of intact microsomes exhibited a nonlinear Arrhenius plot, whereas detergent-modified microsomes showed a linear temperature response. 4. Treatment of microsomes with phospholipase C and toluene-2,4-diisocyanate resulted in an apparent loss of about 65% and 85% of the original glucose-6-phosphatase activity and was closely correlated with hydrolysis and chemical modification of phosphatidylethanolamine, respectively. These apparent inactivations could be reversed by addition of Triton X-114 alone without any phospholipid supplementation. These observations indicate that glucose-6-phosphatase is buried within the microsomal membrane, not exposed on either side. They also suggest that phospholipids are involved in the glucose-6-phosphate transport mechanism.
    [Abstract] [Full Text] [Related] [New Search]