The precursor of acid alpha-glucosidase is synthesized as a membrane-bound enzyme.
A pulse-chase study in human skin fibroblasts showed that a 110 kDa precursor of acid alpha-glucosidase was synthesized as a membrane-bound protein, which was solubilized in vitro not by mannose 6-phosphate or 1M KCl but by Triton X-100 or trypsin. This 110 kDa precursor form bound to the membrane was detected in control fibroblasts treated with tunicamycin and in I-cell disease fibroblasts as well. The precursors in human placenta were found also in the membrane fraction. It was concluded that the newly synthesized acid alpha-glucosidase precursor is located on the surface of the membrane, and the phosphomannosyl receptor does not participate in the enzyme-membrane binding.
Tsuji
A
A
Division of Inherited Metabolic Disease, National Institute of Neuroscience, Tokyo, Japan.
Suzuki
Y
Y
D002462:Cell Membrane / Q000201:enzymology; D002478:Cells, Cultured; D002850:Chromatography, Gel; D005260:Female; D005347:Fibroblasts / Q000201:enzymology; D006801:Humans; D066298:In Vitro Techniques; D007930:Leucine / Q000378:metabolism; D010920:Placenta / Q000201:enzymology; D000520:alpha-Glucosidases / Q000096:biosynthesis*
D000520:alpha-Glucosidases; D007930:Leucine