Related Experiment Videos
Light rough endoplasmic reticulum membranes re-appear before heavy rough membranes after feeding starved MPC-11 cells
Abstract:
In 48 hr starved MPC-11 cells smooth (S) endoplasmic reticulum (ER) membranes accounted for more than 80% of the total ER membrane fraction. After 2 1/2 hr feeding the amount of S membranes was reduced to below 55% while light rough (LR) membranes had increased from about 16% of the total to 42%. The percentage of heavy rough (HR) membranes only showed a minor increase during the incubation period. The results show that following an accumulation of S membranes in starved cells the LR membranes 're-appear' more rapidly than the HR membranes. This difference in behaviour provides further support to the concept that LR and HR membranes represent distinct domains of the ER system.
Insights
Starved cells accumulate smooth endoplasmic reticulum (ER) membranes. Upon refeeding, light rough ER membranes reappear faster than heavy rough ER membranes, indicating distinct ER domains.
Area of Science:
- Cell Biology
- Membrane Biology
Background:
- The endoplasmic reticulum (ER) exists as distinct membrane domains, including smooth (S) and rough (R) ER.
- The dynamic interconversion and distinct behaviors of these domains are not fully understood.
Purpose of the Study:
- To investigate the dynamic changes in smooth, light rough, and heavy rough ER membrane fractions in MPC-11 cells after refeeding following starvation.
- To provide further evidence for the concept of distinct domains within the ER system.
Main Methods:
- MPC-11 cells were subjected to a 48-hour starvation period.
- Cells were then refed for 2.5 hours.
- The relative proportions of smooth (S), light rough (LR), and heavy rough (HR) ER membrane fractions were quantified.
Main Results:
- In starved cells, smooth ER membranes constituted over 80% of the total ER membrane fraction.
- After 2.5 hours of refeeding, smooth ER membranes decreased to below 55%, while light rough ER membranes increased significantly from 16% to 42%.
- Heavy rough ER membranes showed only a minor increase during the incubation period, with light rough membranes reappearing more rapidly than heavy rough membranes.
Conclusions:
- The rapid reappearance of light rough ER membranes compared to heavy rough ER membranes post-starvation supports the hypothesis that these represent distinct functional domains within the endoplasmic reticulum.
- These findings contribute to understanding the plasticity and compartmentalization of the ER membrane system.