Adenine-induced hypoxanthine release from IMP-enriched human erythrocytes.

Adenine uptake and hypoxanthine release by IMP-enriched human erythrocytes has been studied. The presence of IMP within the erythrocytes leads to an increase in the rate of adenine incorporation. Adenine is taken up by IMP-enriched erythrocytes as AMP, even when intracellular 5-phosphoribosyl-1-pyrophosphate concentration is undetectable and too low to allow IMP synthesis from hypoxanthine. During adenine uptake and AMP synthesis, hypoxanthine is released by the cells. The possibility that 5-phosphoribosyl-1-pyrophosphate, necessary for AMP synthesis, is formed through the hypoxanthine guanine phosphoribosyltransferase-catalyzed IMP pyrophosphorolysis is considered.