Biosynthesis of diphosphoinositide

Michell, Robert Hall (1965). Biosynthesis of diphosphoinositide. University of Birmingham. Ph.D.

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Abstract

1. A "mitochondrial” fraction from brain, incubated with 32Pi, synthesised di- and tri-phosphoinositides (DPI and TPl).
2. A mitochondrial fraction from liver, incubated under similar conditions, synthesised DPI.
3. The synthesis was associated with the presence of mitochondria.
4. Oligomycin prevented the labelling of both ATP and DPI. Thus, DPI is not involved in mitochondrial divalent cation accumulation.
5. Phosphatidylinositol (PI) can be phosphorylated to DPI by 52 subcellular fractions from liver, with Y-32P-ATP as the phosphate donor.
6. The biosynthesis of DPI requires Mg++ (or Mn++) ions, PI and ATP.
7. The synthesis occurs mainly in the nuclear and microsomal fractions from rat liver. The mitochondrial fraction is almost inactive.
8. Marker enzymes studies have shown that the distributions of DPI synthesising activity and 5'-nucleotidase are very similar, indicating that DPI synthesis may be localised in the plasma membrane of the liver cell.
9. The possibility that DPI and TPI may be characteristic constituents of plasma membrane systems is discussed in relation to high turnover rates and possible functions.

Type of Work:

Thesis (Doctorates > Ph.D.)

Award Type:

Doctorates > Ph.D.

Supervisor(s):