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Nilanjan Bhowmick AIR 3, CSIR NET (Earth Science)
Anjali Rah posted an Question
August 29, 2020 • 00:53 am
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30 points
30 points
- IIT JAM
- Biotechnology (BT)
How lamellar and tubular er are formed
how lamellar and tubular er are formed..need this ans if anyone can solve plz reply me fast stuck in this
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Anup Padwal
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Tubular form is found in SER and is dynamic in nature, i.e., it is associated with membrane movements, fission and fusion between membranes of cytocavity network and they are branched structures forming the reticular system along with the cisternae and vesicles. lamellar form are found on rough endoplasmic reticulum and formed due to accumulation of ribosome.
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Abhijeet Gaurav Best Answer
The ER plays a number of roles within the cell, from protein synthesis and lipid metabolism to detoxification of the cell. Cisternae, each of the small folds of the endoplasmic reticulum, are commonly associated with lipid metabolism. This creates the plasma membrane of the cell, as well as additional endoplasmic reticulum and organelles. They also appear to be important in maintaining the Ca2+ balance within the cell and in the interaction of the ER with mitochondria. This interaction also influences the aerobic status of the cell. ER sheets appear to be crucial in the response of the organelle to stress, especially since cells alter their tubules-to-sheets ratio when the number of unfolded proteins increases. Occasionally, apoptosis is induced by the ER in response to an excess of unfolded protein within the cell. When ribosomes detach from ER sheets, these structures can disperse and form tubular cisternae. Although ER sheets and tubules appear to have distinct functions, there isn’t a perfect delineation of roles. For instance, in mammals tubules and sheets can interconvert, making the cells adaptable to various conditions. The relationship between structure and function in the ER has not been completely elucidated. The high-curvature of ER tubules is stabilized by the presence of proteins called reticulons and DP1/Yop1p. Reticulons are membrane-associated proteins encoded by four genes in mammals (RTN1-4). These proteins localize to ER tubules and the curved edges of ER sheets. DP1/Yop1p are a class of integral membrane proteins involved in stabilizing the structure of ER cisternae. Both reticulons and DP1/Yop1 proteins form oligomers and interact with the cytoskeleton. Oligomerization seems to be one of the mechanisms used by these proteins to shape the lipid bilayer into a tubule. Additionally, they also appear to use a wedge-like structural motif that causes the membrane to curve. These two classes of proteins are redundant, since the overexpression of one protein can compensate for the lack of the other protein. The construction of the ER is intimately involved with the presence of cytoskeletal elements, especially microtubules. ER membranes, especially cisternae, move and branch along microtubules. When microtubule structure is temporarily disrupted, the ER network collapses and reforms only after the microtubule cytoskeleton is reestablished. In addition, changes to the pattern of microtubule polymerization are reflected in changes to ER morphology.