The intracellular location of hepatic fructose 1,6-biphosphate aldolase

Foemmel et al. (J. Biol. Chem. 250, 1892-1897, 1975) have presented evidence that rat liver aldolase exists in situ as a specific complex with the endoplasmic reticulum. In the present study we have examined the alternative possibility that binding of enzyme to the particulate element represents an artifact of the dilution of the ionic constituents of the cytoplasmic milieu. To this end, procedures were developed for homogenization and subfractionation which effected less than a 3-fold dilution of the intracellular content. Using these procedures, virtually all of the liver aldolase was recovered in the soluble supernatant fraction. We conclude that aldolase is not associated with the endoplasmic reticulum in situ.