Purification of plasma membranes from rat mammary gland by a density perturbation procedure

Abstract
A highly purified plasma membrane fraction was obtained from a microsomal subfraction of rat mammary gland after treatment with digitonin to increase its density. The purified membranes were enriched 70‐fold overall in 5′‐nucleotidase with essentially no contamination from glactosyltransferase, succinate‐INT reductase, or NADPH‐cytochrome c reductase. The mermbranes were also highly enriched in sialoglycoproteins.