Stacked endoplasmic reticulum sheets are connected by helicoidal membrane motifs.
Cell
; 154(2): 285-96, 2013 Jul 18.
Article
em En
| MEDLINE
| ID: mdl-23870120
ABSTRACT
The endoplasmic reticulum (ER) often forms stacked membrane sheets, an arrangement that is likely required to accommodate a maximum of membrane-bound polysomes for secretory protein synthesis. How sheets are stacked is unknown. Here, we used improved staining and automated ultrathin sectioning electron microscopy methods to analyze stacked ER sheets in neuronal cells and secretory salivary gland cells of mice. Our results show that stacked ER sheets form a continuous membrane system in which the sheets are connected by twisted membrane surfaces with helical edges of left- or right-handedness. The three-dimensional structure of tightly stacked ER sheets resembles a parking garage, in which the different levels are connected by helicoidal ramps. A theoretical model explains the experimental observations and indicates that the structure corresponds to a minimum of elastic energy of sheet edges and surfaces. The structure allows the dense packing of ER sheets in the restricted space of a cell.
Texto completo:
1
Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Glândula Parótida
/
Encéfalo
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Retículo Endoplasmático
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Células Acinares
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Neurônios
Limite:
Animals
Idioma:
En
Ano de publicação:
2013
Tipo de documento:
Article