抄録
Intracellular transport of two lysosomal enzymes, acid α-glucosidase and, β-hexosaminidase, was analyzed in human fibroblasts. The precursors of β-hexosaminidase in normal fibroblasts were released from the membrane fraction by treatment with mannose 6-phosphate, but the precursor of α-glucosidase was not. Percoll density gradient centrifugation revealed a normal amount of acid α-glucosidase activity in heavy lysosomes in I-cell disease fibroblasts despite impaired maturation and defective phosphorylation, and β-hexosaminidase activity was markedly reduced in lysosomes. It was concluded that the membrane-bound precursor of acid α-glucosidase is transported to lysosomes by a phosphomannosyl receptor-independent system although the enzyme lacks the recognition marker for the phosphomannosyl receptor and processing of an intermediate form to mature forms does not occur in this disease.
