[3H]Inositol incorporation into phosphoinositides of pig reticulocytes.
Phosphatidylinositol (PI), phosphatidylinositol 4-phosphate (PIP) and phosphatidylinositol 4,5-bisphosphate (PIP2) of pig reticulocytes were extensively labelled when these cells were incubated with [3H]inositol. In marked contrast, a total lack of [3H]inositol labelling of phosphoinositides was observed in mature erythrocytes. Phosphoinositides of both reticulocytes and mature erythrocytes were labelled with 32P but the labelling in reticulocytes was several-fold higher than in mature erythrocytes. Inclusion of Ca2+ (2 mM)+ ionophore A23187 (2 micrograms/ml) during the labelling experiments substantially reduced the radioactivity incorporation into phosphoinositides of reticulocytes. When [3H]inositol-prelabelled reticulocytes were treated with Ca2+ + A23187 the levels of radioactive PI and PIP2 did not change significantly. However, the PIP pool exhibited a remarkable sensitivity to Ca2+ as shown by a 75% increase in its radioactivity over the control. The ability to incorporate [3H]inositol into phosphoinositides remains transitorily intact in the reticulocyte stage. Thus, pig reticulocytes offer a suitable model in which to explore the physiological role of phosphoinositides in relation to cellular maturation process.
D000818:Animals; D000001:Calcimycin / Q000494:pharmacology; D002118:Calcium / Q000494:pharmacology; D004533:Egtazic Acid / Q000494:pharmacology; D007294:Inositol / Q000378:metabolism*; D010710:Phosphates / Q000378:metabolism; D018129:Phosphatidylinositol Phosphates; D010716:Phosphatidylinositols / Q000378:metabolism*; D012156:Reticulocytes / Q000378:metabolism*; D013552:Swine
D010710:Phosphates; D018129:Phosphatidylinositol Phosphates; D010716:Phosphatidylinositols; D000001:Calcimycin; D007294:Inositol; D004533:Egtazic Acid; D002118:Calcium