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Golgi fractions isolated from rat liver homogenates have been resolved into membrane and
content subfractions by treatment with 100 mM Na2CO3 pH 11.3. This procedure permitted
extensive extraction of content proteins and lipoproteins, presumably because it caused
an alteration of Golgi membranes that minimized the reformation of closed vesicles. The
type and degree of contamination of the fractions was assessed by electron microscopy
and biochemical assays. The membrane subfraction retained 15% of content proteins and
lipids, and these could not be removed by various washing procedures. The content
subfraction was contaminated by both membrane fragments and vesicles and accounted for 5
to 10% of the membrane enzyme activities of the original Golgi fraction. The lipid
compositions of the subfractions was determined, and the phospholipids of both membrane
and content were found to be uniformly labeled with [33P]phosphate administered in vivo.
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