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Topology of molecular machines of the endoplasmic reticulum: a compilation of proteomics and cytological data.

Lavoie C, Paiement J - Histochem. Cell Biol. (2008)

Bottom Line: In addition, the ER is involved in the metabolism and degradation of specific xenobiotics and endogenous biosynthetic products.A variety of proteomics studies have been reported on different subcompartments of the ER providing an ER protein dictionary with new data being made available on many protein complexes of relevance to the biology of the ER including the ribosome, the translocon, coatomer proteins, cytoskeletal proteins, folding proteins, the antigen-processing machinery, signaling proteins and proteins involved in membrane traffic.This review examines proteomics and cytological data in support of the presence of specific molecular machines at specific sites or subcompartments of the ER.

View Article: PubMed Central - PubMed

Affiliation: Département de pharmacologie, Faculté de Médecine, Université de Sherbrooke, Sherbrooke, QC, Canada, J1H 5N4.

ABSTRACT
The endoplasmic reticulum (ER) is a key organelle of the secretion pathway involved in the synthesis of both proteins and lipids destined for multiple sites within and without the cell. The ER functions to both co- and post-translationally modify newly synthesized proteins and lipids and sort them for housekeeping within the ER and for transport to their sites of function away from the ER. In addition, the ER is involved in the metabolism and degradation of specific xenobiotics and endogenous biosynthetic products. A variety of proteomics studies have been reported on different subcompartments of the ER providing an ER protein dictionary with new data being made available on many protein complexes of relevance to the biology of the ER including the ribosome, the translocon, coatomer proteins, cytoskeletal proteins, folding proteins, the antigen-processing machinery, signaling proteins and proteins involved in membrane traffic. This review examines proteomics and cytological data in support of the presence of specific molecular machines at specific sites or subcompartments of the ER.

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Different subcompartments of the endoplamic reticulum. The ER is composed of continuous but distinct subdomains. a The nuclear envelope (NE) is shown with nuclear pores and ribosomal particles attached to the outer membrane. b The rough ER (rER) is continuous with the NE and consists of stacked flattened saccules, whose limiting membranes have numerous attached ribosomal particles. c Transitional ER (tER) is composed of a rER subdomain continuous with the rER and a smooth ER (sER) subdomain consisting of buds and tubules devoid of associated ribosomes (arrowhead points to a coated bud). d In some cells (e.g., steroid secreting cells and hepatocytes) the sER is composed of a large network of interconnecting tubules showing tripartite junctions (arrows) and fenestrations. Micrograph in C is courtesy of Christian Zuber and Jurgen Roth
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Fig1: Different subcompartments of the endoplamic reticulum. The ER is composed of continuous but distinct subdomains. a The nuclear envelope (NE) is shown with nuclear pores and ribosomal particles attached to the outer membrane. b The rough ER (rER) is continuous with the NE and consists of stacked flattened saccules, whose limiting membranes have numerous attached ribosomal particles. c Transitional ER (tER) is composed of a rER subdomain continuous with the rER and a smooth ER (sER) subdomain consisting of buds and tubules devoid of associated ribosomes (arrowhead points to a coated bud). d In some cells (e.g., steroid secreting cells and hepatocytes) the sER is composed of a large network of interconnecting tubules showing tripartite junctions (arrows) and fenestrations. Micrograph in C is courtesy of Christian Zuber and Jurgen Roth

Mentions: The ER is a dynamic organelle essential for cell life. The main subdomains of the ER include the nuclear envelope (NE), rough ER (rER), and transitional ER (tER), each with its own characteristic structure and function. The NE forms a shell around the nucleus. The shell typically consists of a flattened saccule closely applied to nuclear chromatin and showing multiple discontinuities or nuclear pores (Fig. 1a). The rER is continuous with the NE and consists mostly of stacked, flattened saccules. Each saccule is limited by membranes with attached ribosomal particles (Fig. 1b). The tER is composed of two distinct but continuous membrane domains: a rough domain characterized by the presence of attached ribosomes and a smooth domain (sER), giving rise to membrane buds and tubules (Fig. 1c). Clusters of vesicles, and tubules are often observed closely associated with the tER and represent the intermediate compartment, also called ER-Golgi Intermediate Compartment (ERGIC), vesiculo-tubular clusters (VTCs) or pre-Golgi intermediates (Bannykh et al. 1996; Hauri et al. 2000; Saraste and Kuismanen 1992; Fan et al. 2003). In certain cell types (such as steroid-synthesizing cells or hepatocytes) the smooth ER is extensive and consists of a network of interconnecting tubules limited by smooth membranes devoid of attached ribosomes. The tubules are linked by tripartite junctions and limit cytoplasmic regions often devoid of large organelles (Fig. 1d).Fig. 1


Topology of molecular machines of the endoplasmic reticulum: a compilation of proteomics and cytological data.

Lavoie C, Paiement J - Histochem. Cell Biol. (2008)

Different subcompartments of the endoplamic reticulum. The ER is composed of continuous but distinct subdomains. a The nuclear envelope (NE) is shown with nuclear pores and ribosomal particles attached to the outer membrane. b The rough ER (rER) is continuous with the NE and consists of stacked flattened saccules, whose limiting membranes have numerous attached ribosomal particles. c Transitional ER (tER) is composed of a rER subdomain continuous with the rER and a smooth ER (sER) subdomain consisting of buds and tubules devoid of associated ribosomes (arrowhead points to a coated bud). d In some cells (e.g., steroid secreting cells and hepatocytes) the sER is composed of a large network of interconnecting tubules showing tripartite junctions (arrows) and fenestrations. Micrograph in C is courtesy of Christian Zuber and Jurgen Roth
© Copyright Policy
Related In: Results  -  Collection

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getmorefigures.php?uid=PMC2228376&req=5

Fig1: Different subcompartments of the endoplamic reticulum. The ER is composed of continuous but distinct subdomains. a The nuclear envelope (NE) is shown with nuclear pores and ribosomal particles attached to the outer membrane. b The rough ER (rER) is continuous with the NE and consists of stacked flattened saccules, whose limiting membranes have numerous attached ribosomal particles. c Transitional ER (tER) is composed of a rER subdomain continuous with the rER and a smooth ER (sER) subdomain consisting of buds and tubules devoid of associated ribosomes (arrowhead points to a coated bud). d In some cells (e.g., steroid secreting cells and hepatocytes) the sER is composed of a large network of interconnecting tubules showing tripartite junctions (arrows) and fenestrations. Micrograph in C is courtesy of Christian Zuber and Jurgen Roth
Mentions: The ER is a dynamic organelle essential for cell life. The main subdomains of the ER include the nuclear envelope (NE), rough ER (rER), and transitional ER (tER), each with its own characteristic structure and function. The NE forms a shell around the nucleus. The shell typically consists of a flattened saccule closely applied to nuclear chromatin and showing multiple discontinuities or nuclear pores (Fig. 1a). The rER is continuous with the NE and consists mostly of stacked, flattened saccules. Each saccule is limited by membranes with attached ribosomal particles (Fig. 1b). The tER is composed of two distinct but continuous membrane domains: a rough domain characterized by the presence of attached ribosomes and a smooth domain (sER), giving rise to membrane buds and tubules (Fig. 1c). Clusters of vesicles, and tubules are often observed closely associated with the tER and represent the intermediate compartment, also called ER-Golgi Intermediate Compartment (ERGIC), vesiculo-tubular clusters (VTCs) or pre-Golgi intermediates (Bannykh et al. 1996; Hauri et al. 2000; Saraste and Kuismanen 1992; Fan et al. 2003). In certain cell types (such as steroid-synthesizing cells or hepatocytes) the smooth ER is extensive and consists of a network of interconnecting tubules limited by smooth membranes devoid of attached ribosomes. The tubules are linked by tripartite junctions and limit cytoplasmic regions often devoid of large organelles (Fig. 1d).Fig. 1

Bottom Line: In addition, the ER is involved in the metabolism and degradation of specific xenobiotics and endogenous biosynthetic products.A variety of proteomics studies have been reported on different subcompartments of the ER providing an ER protein dictionary with new data being made available on many protein complexes of relevance to the biology of the ER including the ribosome, the translocon, coatomer proteins, cytoskeletal proteins, folding proteins, the antigen-processing machinery, signaling proteins and proteins involved in membrane traffic.This review examines proteomics and cytological data in support of the presence of specific molecular machines at specific sites or subcompartments of the ER.

View Article: PubMed Central - PubMed

Affiliation: Département de pharmacologie, Faculté de Médecine, Université de Sherbrooke, Sherbrooke, QC, Canada, J1H 5N4.

ABSTRACT
The endoplasmic reticulum (ER) is a key organelle of the secretion pathway involved in the synthesis of both proteins and lipids destined for multiple sites within and without the cell. The ER functions to both co- and post-translationally modify newly synthesized proteins and lipids and sort them for housekeeping within the ER and for transport to their sites of function away from the ER. In addition, the ER is involved in the metabolism and degradation of specific xenobiotics and endogenous biosynthetic products. A variety of proteomics studies have been reported on different subcompartments of the ER providing an ER protein dictionary with new data being made available on many protein complexes of relevance to the biology of the ER including the ribosome, the translocon, coatomer proteins, cytoskeletal proteins, folding proteins, the antigen-processing machinery, signaling proteins and proteins involved in membrane traffic. This review examines proteomics and cytological data in support of the presence of specific molecular machines at specific sites or subcompartments of the ER.

Show MeSH
Related in: MedlinePlus