The incorporation of 32P from triphosphate into polyphosphoinositides [γ-32P]adenosine and phosphatidic acid in erythrocyte membranes

Abstract

• 1.

  1. Erythrocyte ghosts incubated with [γ-³²P]ATP incorporate radioactivity into diphosphoinositide, triphosphoinositide, phosphatidic acid, and into at least one unidentified lipid.

• 2.

  2. Over 90% of the radioactivity incorporated into the polyphosphoinositides is in the monoesterified phosphates.

• 3.

  3. Exogenous phosphatidyl inositol increases the labeling in diphosphoinositide by about 30% and in the unidentified compound by about 200%. The labeling in triphosphoinositide is inhibited.

• 4.

  4. Kinetic studies of the labeling of the polyphosphoinsitides fail to provide evidence that the exchange of phosphate in the monoesterified positions is an intermediate reaction in the magnesium-dependent, sodium and potassium-activated ATPase.