HVEM tomography of the trans-Golgi network: structural insights and identification of a lace-like vesicle coat.
J Cell Biol
; 127(1): 29-38, 1994 Oct.
Article
en En
| MEDLINE
| ID: mdl-7929568
High voltage electron microscopy and computer axial tomography have been used to study the 3-D structure of trans-Golgi cisternae and trans-Golgi networks (TGNs) in NRK cells. Both structures were specifically labeled by photoconversion of a fluorescent analogue of ceramide using a modification of the techique of Pagano et al. (J. Cell Biol. 1991. 113: 1267-1279). Regions of the Golgi ribbon in fixed, stained cells were cut in 250-nm sections and analyzed by tilt series microscopy and subsequent tomographic reconstruction. Resolution of the reconstructions ranged from 6 to 10 nm. The size and structure of the TGN varied considerably throughout the Golgi ribbon; all reconstructions were made from regions with pronounced TGN. Most regions analyzed contained multiple (2-4) Golgi cisternae that stain with ceramide. These "peel off" from the closely stacked cisternae and are continuous at their ends with tubules that contribute to the TGN. Most vesicular profiles visualized in the TGN are connected to TGN tubules. The budding of vesicles appears to occur synchronously along the length of a TGN tubule. Two distinct coats were visualized on budding vesicles: clathrin cages and a novel, lace-like structure. Individual TGN tubules produce vesicles of only one coat type. These observations lead to the following predictions: (a) sorting of molecules must occur prior to the formation of TGN tubules; (b) vesicle formation takes place almost synchronously along a given TGN tubule; and (c) lace-like coats form an exocytic vesicles.
Texto completo:
1
Colección:
01-internacional
Base de datos:
MEDLINE
Asunto principal:
Microscopía Electrónica
/
Aparato de Golgi
Tipo de estudio:
Diagnostic_studies
Límite:
Animals
Idioma:
En
Revista:
J Cell Biol
Año:
1994
Tipo del documento:
Article
Pais de publicación:
Estados Unidos