Reticulum, endoplasmic smooth

Figure 2. Reporting of cytosolic free calcium levels by indo-1. Increases in cytosolic calcium, due either to entry of extracellular calcium via calcium channels or to release of intracellular calcium sequestered in organelles such as smooth endoplasmic reticulum, results in formation of the indo-l-calcium complex. Fluorescence intensity at 400 nm (excitation at 340 nm) is proportional to the concentration of this complex the dissociation constant for this complex is about 250 nff (24), making this probe useful for detecting calcium activities in the range of 25 to 2500 nJ. ...

Figure 3. Reporting of intracellular calcium sequestration by chlorotetracycline (CTC). CTC preferentially partitions into cell membranes and its fluorescence in this environment is sensitive to calcium bound to the membrane therefore its signal (excitation AOO nm, emission 530 nm) will come largely from organelles that bind or sequester calcium, such as smooth endoplasmic reticulum or mitochondria. Release of calcium from such organelles is accompanied by dissociation of the calcium-CTC complex, a decrease in CTC fluorescence and efflux of unbound probe from the organelle and from the cell.

Figure 25-2. The formation and secretion of (A) chylomicrons by an intestinal cell and (B) very low density lipoproteins by a hepatic cell. (RER, rough endoplasmic reticulum SER, smooth endoplasmic reticulum G, Golgi apparatus N, nucleus C, chylomicrons VLDL, very low density lipoproteins E, endothelium SD, space of Disse, containing blood plasma.) Apolipoprotein B, synthesized in the RER, is incorporated into lipoproteins in the SER, the main site of synthesis of triacylglycerol. After addition of carbohydrate residues in G, they are released from the cell by reverse pinocytosis. Chylomicrons pass into the lymphatic system. VLDL are secreted into the space of Disse and then into the hepatic sinusoids through fenestrae in the endothelial lining.

Their hydroxylated products are more water-soluble than their generally lipophilic substrates, facilitating excretion Liver contains highest amounts, but found In most If not all tissues. Including small Intestine, brain, and lung Located in the smooth endoplasmic reticulum or in mitochondria (steroidogenic hormones)... 

FIGURE 1-5 Detail of the nuclear envelope showing a nuclear pore (single arrow) and the outer leaflet connected to the smooth endoplasmic reticulum (ER) (double arrows). Two cisternae of the rough ER with associated ribosomes are also present. X80,000. 

The smooth endoplasmic reticulum calcium pumps (SERCA) found in brain were first identified in sarcoplasmic reticulum. The three isoforms of SERCA are products of separate genes SERCA-1 is expressed in fast-twitch skeletal muscle SERCA-2a in cardiac/slow-twitch muscle SERCA-2b, an alternatively spliced form, is expressed in smooth muscle and non-muscle tissues SERCA-3 is... 

Gillette, D.M., R.D. Corey, W.G. Helferich, J.M. MacFarland, L.J. Lowenstine, D.E. Moody, B.D. Hammock, and L.R. Shull. 1987a. Comparative toxicology of tetrachlorobiphenyls in mink and rats. I. Changes in hepatic enzyme activity and smooth endoplasmic reticulum volume. Fundam. Appl. Toxicol. 8 5-14. 

Metofluthrin (I) The committee determined that the new data were sufficient to support a mitogenic mode of action for the development of liver tumors in rats exposed to metofluthrin in the carcinogenicity study. The report summarized mode of action study data that characterized effects such as increased P450 enzyme levels, increased smooth endoplasmic reticulum, hepatocellular hypertrophy, hepatocellular proliferation, and inhibition of intracellular communication, which were described as steps leading to tumor development via a nongenotoxic mechanism (i.e., mitogenicity). Some of these studies used sodium phenobarbital as a positive control,... 

Yoshida S. Isolation of smooth endoplasmic reticulum and tonoplast from etiolated mung bean hypocotyls. in Methods in Enzymology, Vol. 228 (Walter H, Johansson G, ed.), Academic Press, New York, 1994, pp. 482-489. 

Stelzner DJ. The relationship between synaptic vesicles, Golgi apparatus, and smooth endoplasmic reticulum A developmental study using the zinc iodide-osmium technique. Z Zellforsch 1971 120 332-345. 

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