Immunomicroscopic localization of aminopeptidase N in the pig enterocyte. Implications for the route of intracellular transport.
The subcellular localization of aminopeptidase N (EC 3.4.11.2) in the pig enterocyte was investigated by immunofluorescence and immunoelectron microscopy (immunogold staining). By indirect immunofluorescence on either frozen or paraffin-embedded sections, a very intense staining in the microvillar membrane and a weak intracellular staining was demonstrated. No staining was detected in the basolateral membrane. Likewise, the immunogold labelling on Epon-embedded sections was concentrated in the microvillar membrane, whereas the basolateral membrane did not contain significant amounts of labelling. Labelling was demonstrated in the Golgi apparatus and in a minor fraction of the intracellular smooth vesicles positioned between the Golgi apparatus and the microvillar membrane. These observations are compatible with the view that newly synthesized aminopeptidase N is delivered directly to the microvillar membrane by smooth vesicles having a diameter about 70 to 100 nm and does not pass the basolateral membrane on its way to the brush border membrane.
D000626:Aminopeptidases / Q000378:metabolism*; D000818:Animals; D018826:CD13 Antigens; D004847:Epithelial Cells; D004848:Epithelium / Q000201:enzymology / Q000648:ultrastructure; D005455:Fluorescent Antibody Technique; D007082:Ileum / Q000166:cytology / Q000201:enzymology* / Q000648:ultrastructure; D008854:Microscopy, Electron; D013552:Swine
D000626:Aminopeptidases; D018826:CD13 Antigens