Addition of wortmannin to normal rat kidney cells caused a redistribution of the lysosomal type I integral membrane proteins Igp110 and Igp120 to a swollen vacuolar compartment. This compartment did not contain the cation independent mannose 6-phosphate receptor and was depleted in acid hydrolases. It was distinct from another swollen vacuolar compartment containing the cation independent mannose 6-phosphate receptor. The swollen Igp110-positive compartment was accessible to a monoclonal antibody against Igp120 added extracellularly, showing that it had the characteristics of an endosomal compartment. Wortmannin had no gross morphological effect on the trans-Golgi network or lysosomes nor any effect on the delivery to the trans-Golgi network of endocytosed antibodies against the type I membrane protein TGN38. We propose that the observed effects of wortmannin were due to inhibition of membrane traffic between cation independent mannose 6-phosphate receptor-positive late endosomes and the trans-Golgi network and to inhibition of membrane traffic between a novel Igp120-positive, cation independent mannose 6-phosphate receptor-negative late endosomal compartment and lysosomes. The effects of wortmannin suggest a function for a phosphatidylinositol 3-kinase(s) in regulating membrane traffic in the late endocytic pathway.
The effect of wortmannin on the localisation of lysosomal type I integral membrane glycoproteins suggests a role for phosphoinositide 3-kinase activity in regulating membrane traffic late in the endocytic pathway
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B.J. Reaves, N.A. Bright, B.M. Mullock, J.P. Luzio; The effect of wortmannin on the localisation of lysosomal type I integral membrane glycoproteins suggests a role for phosphoinositide 3-kinase activity in regulating membrane traffic late in the endocytic pathway. J Cell Sci 1 April 1996; 109 (4): 749–762. doi: https://doi.org/10.1242/jcs.109.4.749
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