Endoplasmic reticulum overview

Cellular location of ribosomes In eukaryotic cells, the ribosomes are either "free" in the cytosol or are in close association with the endoplasmic reticulum (which is then known as the "rough" ER or RER). The RER-associated ribosomes are responsible for synthesizing proteins that are to be exported from the cell, as well as those that are destined to become integrated into plasma, ER, or Golgi membranes, or incorporated into lysosomes (see p. 167 loan overview of the latter process). [Note Mitochondria contain their own set of ribosomes and their own unique, circular DNA.]... 

Pfeffer, S. R., and J. E. Rothman, Biosynthetic protein transport and sorting by the endoplasmic reticulum and Golgi. Ann. Rev. Biochem. 56 829, 1987. An excellent overview of the major features of protein targeting in eukaryotic cells. 

Figure 6.1. Overview of cellular calcium transport. Calcium enters the cell through voltage- or ligand-gated channels (left). It is extmded by ATP-driven pumps or by sodium antiport (right). Both the mitochondria and the endoplasmic reticulum serve as intracellular calcium stores. The cytosolic concentration is kept at -100 nM under resting conditions. CaM Calmodulin.

A FIGURE 18-1 Overview of synthesis of major membrane lipids and their movement into and out of cells. Membrane lipids (e.g., phospholipids, cholesterol) are synthesized through complex multienzyme pathways that begin with sets of water-soluble enzymes and intermediates in the cytosol (D) that are then converted by membrane-associated enzymes into water-insoluble products embedded in the membrane (B), usually at the interface between the cytosolic leaflet of the endoplasmic reticulum (ER) and the cytosol. Membrane lipids can move from the ER to other organelles (H), such as the Golgi apparatus or the mitochondrion, by either vesicle-mediated or other poorly defined mechanisms. Lipids can move into or out of cells by plasma-membrane transport proteins or by lipoproteins. Transport proteins similar to those described in Chapter 7 that move lipids (0) include sodium-coupled symporters that mediate import CD36 and SR-BI superfamily proteins that can mediate... 

Cellular overview was created using this data to simplify the complexity and for elaborative interpretation of the data The compartments included are Nucleus, Golgi apparatus. Endoplasmic Reticulum, and the Cell Membrane. The fluxes and the choke-point reactions are also marked to indicate the critical reactions in the pathway (Fig.7). 

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