Compartmental distribution of β-hexosaminidase isoenzymes in I-cell fibroblasts

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Abstract
A characteristic of the human lysosomal disorder I-cell disease is an abnormal excretion of most lysosomal hydrolases, including .beta.-N-acetyl-D-glucosaminidase (EC 3.2.1.30; .beta.-hexosaminidase) by cultured skin fibroblasts. Treatment of I-cell cultures with cycloheximide or tunicamycin demonstrated that I-cell fibroblasts rapidly excrete all newly synthesized .beta.-hexosaminidase, 2 qualitatively distinct pools of .beta.-hexosaminidase isoenzymes exist inside I-cell fibroblasts, one of which is a rapid-turnover excretory pool and the induction of an abnormal glycosylation of .beta.-hexosaminidase by tunicamycin in normal or I-cell fibroblast cultures does not affect subsequent excretion of the enzyme.