title: Dissection of the asynchronous transport of intestinal microvillar hydrolases to the cell surface.
abstract: Novel subcellular fractionation procedures and pulse-chase techniques were used to study the intracellular transport of the microvillar membrane hydrolases sucrase-isomaltase and dipeptidylpeptidase IV in the differentiated colon adenocarcinoma cell line Caco-2. The overall rate of transport to the cell surface was two fold faster for dipeptidylpeptidase IV than for sucrase-isomaltase, while no significant differences were observed in transport rates from the site of complex glycosylation to the brush border. The delayed arrival of sucrase-isomaltase in the compartment where complex glycosylation occurs was only in part due to exit from the endoplasmic reticulum. A major slow-down could be ascribed to maturation in and transit of this enzyme through the Golgi apparatus. These results suggest that the observed asynchronism is due to more than one rate-limiting step along the rough endoplasmic reticulum to trans-Golgi pathway.
mesh_terms: D001692:Biological Transport; D002258:Carbonyl Cyanide m-Chlorophenyl Hydrazone / Q000494:pharmacology; D002451:Cell Compartmentation; D018819:Dipeptidyl Peptidase 4; D004152:Dipeptidyl-Peptidases and Tripeptidyl-Peptidases / Q000378:metabolism*; D004721:Endoplasmic Reticulum / Q000378:metabolism; D005455:Fluorescent Antibody Technique; D006056:Golgi Apparatus / Q000378:metabolism; D006801:Humans; D007413:Intestinal Mucosa / Q000201:enzymology*; D007425:Intracellular Membranes / Q000378:metabolism; D007700:Kinetics; D008854:Microscopy, Electron; D008871:Microvilli / Q000201:enzymology; D009097:Multienzyme Complexes / Q000378:metabolism*; D011499:Protein Processing, Post-Translational; D013394:Sucrase-Isomaltase Complex / Q000378:metabolism*; D014407:Tumor Cells, Cultured
chemical_list: D009097:Multienzyme Complexes; D002258:Carbonyl Cyanide m-Chlorophenyl Hydrazone; D013394:Sucrase-Isomaltase Complex; D004152:Dipeptidyl-Peptidases and Tripeptidyl-Peptidases; D018819:Dipeptidyl Peptidase 4