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Maturation of human lactase‐phlorizin hydrolase Proteolytic cleavage of precursor occurs after passage through the Golgi complex
Author(s) -
Lottaz D.,
Oberholzer T.,
Bähler P.,
Semenza G.,
Sterchi E.E.
Publication year - 1992
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/0014-5793(92)81207-3
Subject(s) - golgi apparatus , brefeldin a , microvillus , microbiology and biotechnology , chemistry , vesicle , intracellular , proteolytic enzymes , biochemistry , phlorizin , biology , endoplasmic reticulum , enzyme , membrane , glucose transporter , endocrinology , insulin
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.