Endoplasmic recticulum

The major type of PTM that has this function is protein disulfide bond formation (33). Disulfide bonds are more stable thermodynamically than the reduced thiols in an oxidizing environment. In eukaryotes, proteins that undergo the secretary pathway start to form disulfide bonds once they are translocated into the endoplasmic recticulum (ER) lumen, which is an oxidizing environment. These disulfide bonds help to stabilize... 

Fig. 4.7. Sectioned cell of Stephanoeca diplocostata Ellis showing a mature intracellular silica costal strip enclosed within a preformed elongated vesicle adjacent to the endoplasmic recticulum (ER) (x 34,000)...

Orsel, J.G. Bartoldus, I. Stegmann. T. Kinetics of fusion between endoplasmic recticulum vesicles in vitro. J. Biol. Chem. 1997, 272 (6). 3369 - 3375. 

Appealing as it is, the hypothesis that the thyroid hormone exerts its entire metabolic effect by stimulation of protein synthesis in mitochondria or in the endoplasmic recticulum is unlikely metabolic effects of the thyroid hormone continue to be expressed when actinomycin D is administered simultaneously [35]. 

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