Immuno-electronmicroscopical localization of a microvillus membrane disaccharidase in the human small-intestinal epithelium with monoclonal antibodies.
Eur J Cell Biol
; 38(1): 6-15, 1985 Jul.
Article
en En
| MEDLINE
| ID: mdl-3896809
The cellular localization of the human intestinal disaccharidase, sucrase-isomaltase, was visualized in ultrathin cryosections by the use of specific monoclonal antibodies [25] followed by protein A-gold. The principle site of immunoreaction concerned the microvillus membrane, which supports current concepts of the localization of these hydrolases. One antibody against sucrase-isomaltase also showed labeling of the Golgi apparatus, apical vesicles, and lysosomes, but not of the basolateral membrane. The labeling of the Golgi complex was uniform, suggesting the absence of accumulation of sucrase-isomaltase in cisternae during its passage through this organelle. Absence of labeling of the basolateral membrane appears to support the view that newly synthesized sucrase-isomaltase is transferred directly from the Golgi complex to the microvillus membrane, bypassing the basolateral membrane. However, the results do not exclude the possibility of a very rapid passage through the basolateral membrane. A substantial fraction of the sucrase-isomaltase occurred in lysosomes, which indicates that this organelle plays a major role in the catabolism of microvillar hydrolases. Transport of sucrase-isomaltase to lysosomes might occur by endocytosis or via the crinophagic pathway. The latter was previously postulated to reflect a regulatory mechanism at the post-Golgi level for the surface expression of microvillar membrane proteins.
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Colección:
01-internacional
Banco de datos:
MEDLINE
Asunto principal:
Disacaridasas
/
Mucosa Intestinal
/
Intestino Delgado
Límite:
Humans
Idioma:
En
Revista:
Eur J Cell Biol
Año:
1985
Tipo del documento:
Article