Maturation of human lactase‐phlorizin hydrolase Proteolytic cleavage of precursor occurs after passage through the Golgi complex

FEBS Letters - Tập 313 - Trang 270-276 - 1992
D. Lottaz1,2, T. Oberholzer3, P. Bähler2, G. Semenza3, E.E. Sterchi1,2
1Institute of Biochemistry and Molecular Biology, University of Berne, CH-3012 Berne, Switzerland
2Department of Pediatrics, Faculty of Medicine, University of Berne, CH-3012 Berne, Switzerland
3Department of Biochemistry, Swiss Federal Institute of Technology, ETH-Zentrum, CH-8092 Zürich, Switzerland

Tóm tắt

Maturation of human intestinal lactase‐phlorizin hydrolase (LPH) requires that a precursor (pro‐LPH) be proteolytically processed to the mature microvillus membrane enzyme (m‐LPH). The subcellular site of this processing is unknown. Using low‐temperature experiments and brefeldin A (BFA), intracellular transport was blocked in intestinal epithelial cells. In Caco‐2 cells incubated at 18°C pro‐LPH was complex‐glycosylated but not cleaved, while at 20°C small amounts of proteolytically processed LPH were observed. These data exclude a pre‐Golgi proteolytic event. BFA completely blocked proteolytic maturation of LPH and lead to an aberrant form of pro‐LPH in both Caco‐2 cells and intestinal explants. Therefore, proteolytic processing of LPH is a post‐Golgi event, occuring either in the trans‐Golgi network, transport vesicles, or after insertion of pro‐LPH into the microvillus membrane.

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FEBS Letters

Tập 313

270-276

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