The migration of labeled phosphatidylcholine from the nuclear-associated endoplasmic reticulum to plasma membranes in L-929 cells |
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Authors: | Ian F Pryme Ezekiel T Quarcoo |
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Institution: | 1. Department of Biochemistry, University of Bergen, ?rstadveien 19, N-5009, Bergen, Norway
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Abstract: | Summary The nuclear-associated endoplasmic reticulum of L-929 cells was found to contain the highest amount of labeled phosphatidylcholine
after a 60 min incubation with14C-choline. Radioactivity was otherwise distributed relatively evenly among other membrane-containing organelles (nuclei, mitochondria,
plasma membranes and endoplasmic reticulum membranes). During a 120 min chase following removal of isotope and addition of
cold choline chloride, there was a considerable reduction in labeled phosphatidylcholine in the NER and nuclei. The decrease
in radioactivity in these fractions was matched by an almost identical increase in the fraction containing mitochondria and
plasma membranes. Separation of mitochondria and plasma membranes by centrifugation on discontinuous gradients showed that14C-choline labeled phosphatidylcholine appeared most rapidly in the plasma membranes. The results indicate that phospholipid
molecules migrate within a short period of time from their site of synthesis in the NER to plasma membranes. |
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Keywords: | phosphatidylcholine nuclei endoplasmic reticulum mitochondria plasma membranes |
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