Light rough endoplasmic reticulum membranes re-appear before heavy rough membranes after feeding starved MPC-11 cells.

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.