Analysis of lactase processing in rabbit.
The proteolytic processing of rabbit intestinal lactase-phlorizin-hydrolase (LPH) was studied by pulse-chase and continuous labeling experiments in organ culture from 15-day-old rabbits in the presence of glycosylation and processing inhibitors. Monensin and brefeldin A inhibited the two proteolytic cleavages of the precursor indicating that they are post-Golgi events as previously reported for the unique cleavage of LPH in man. The inhibition was not related to a concomitant alteration glycosylation; in fact, if trimming was blocked by MDNM the abnormal glycosylated precursor was proteolytically processed normally. Finally the use of the anti-microtubular drug colchicine strongly inhibited both cleavages and caused accumulation of the complex-glycosylated precursor form the brush border fraction indicating that proteolytic events depend on intact microtubule (transport).
Rossi
M
M
Department of Pediatrics, University Federico II of Naples, Italy.
Maiuri
L
L
Salvati
V M
VM
Russomanno
C
C
Auricchio
S
S
D000818:Animals; D020126:Brefeldin A; D002458:Cell Fractionation; D003078:Colchicine / Q000494:pharmacology; D003517:Cyclopentanes / Q000494:pharmacology; D004792:Enzyme Precursors / Q000378:metabolism; D006031:Glycosylation; D006056:Golgi Apparatus / Q000187:drug effects / Q000201:enzymology; D006868:Hydrolysis; D010694:Lactase-Phlorizin Hydrolase / Q000037:antagonists & inhibitors / Q000378:metabolism*; D008871:Microvilli / Q000378:metabolism; D008985:Monensin / Q000494:pharmacology; D009924:Organ Culture Techniques; D011499:Protein Processing, Post-Translational; D011817:Rabbits
D003517:Cyclopentanes; D004792:Enzyme Precursors; D020126:Brefeldin A; D008985:Monensin; D010694:Lactase-Phlorizin Hydrolase; D003078:Colchicine