Translocation of sugars into rat liver lysosomes. Evidence against a common carrier for d-glucose and d-ribose

Abstract

A conflict exists in the literature concerning the mode of translocation of D-glucose and D-ribose across the lysosome membrane. The more rapid net uptake of ribose, when measured by the osmotic-protection technique, has been attributed either to its smaller size and lower hydrogen-bonding capacity, or to a lower affinity for a transport system shared by both sugars. The latency of acid beta-hexosaminidase in isolated rat liver lysosomes was measured after preincubation for periods up to 1 h in various solutions containing glucose and/or ribose, and in some cases sucrose. After confirmation of the superior osmotic protection afforded by glucose (than by ribose), it was shown that a solution 0.125 M in both glucose and ribose provided protection intermediate between that given by 0.25 M-glucose and that given by 0.25 M-ribose. This result is inconsistent with the common-carrier hypothesis.