The presence of plasma membrane enzymes on the surface of bovine milk fat globules

Patton, Stuart; Trams, Eberhard G.

doi:10.1016/0014-5793(71)80624-5

Cited by 67 publications

(24 citation statements)

References 8 publications

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“…Electron microscopic investigation demonstrates how fat droplets are secreted from the bovine mammary gland (Patton and Trams, 1971): the droplets are surrounded by pieces of plasma membrane and little if any cytoplasm is included. Dewben and his collaborators isolated these droplets, formed ghosts from them by freeze-thawing or sonication, and characterized the resulting membranes, concluding that tho properties they found were those of the plasma membrane.…”

Section: Special Approaches To the Isolation Of Plasma Membranesmentioning

confidence: 99%

Plasma Membranes of Mammalian Cells

DePierre

Karnovsky

1973

The Journal of Cell Biology

429

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Section: Special Approaches To the Isolation Of Plasma Membranesmentioning

confidence: 99%

Plasma Membranes of Mammalian Cells

DePierre

Karnovsky

1973

The Journal of Cell Biology

429

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“…Membrane 5'-nucleotidase activity in rat tissues, other than liver, was generally lower (table I). Ray, 1970Lauter et al, 1972Emmelot and Bos, 1969aHinton et al, 1970Evans, 1970Fleischer and Fleischer, 1969Lauter et al, 1972Lutz and Frimmer, 1970 Ebel et al, 1971Giacobino and Perrelet, 1971Giacobino and Perrelet, 1971Avruch and Wallach, 1971McKeel and Jarett, 1970Kidwai et al, 1971Wolff and Jones, 1971Meldolesi et al, 1971Nachman et al, 1971Woodin et al, 1970Patton and Trams, 1971Zentgraf et al, 1971 It should be kept in mind that most membrane preparations are enriched with certain portions of the cell surface only. Such is the case with Neville's liver plasma membrane preparations, where the bile front seems to be isolated preferentially.…”

Section: '-Nucleotidase (Ec 3135)mentioning

confidence: 99%

Enzyme Markers in Characterization of Isolated Plasma Membranes

Solyom

Eg²

1972

Enzyme

159

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A review of the enzyme activities of plasma membranes reveals that none of them characterize plasma membranes universally. Potentially, adenyl cyclase is the best plasma membrane marker enzyme. Species, tissue and sex differences complicate the sole use of enzymes as markers in the characterization of plasma membrane preparations. It is necessary to establish specific enzymological criteria for plasma membrane enzymes to distinguish them from isoenzymes in other subcellular membranes. Standard assays have been suggested for comparative purposes.

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“…Evidence for this process has been obtained from electron-microscopy (Bargmann & Knoop, 1959;Bargmann, Fleischauer & Knoop, 1961) and by biochemical comparison of MFGM with isolated mammary plasma membrane. Both membranes have a similar lipid composition (Keenan, Morr6, Olson, Yunghans & Patton, 1970) and MFGM contains enzymes characteristic of plasma membrane preparations (Dowben, Brunner & Philpott, 1967;Patton & Trams, 1971).…”

mentioning

confidence: 99%

Studies on the structure of milk fat globule membrane

1975

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Milk fat globule membrane was solubilized with sodium dodecyl sulfate and mercaptoethanol and the membrane proteins were separated by SDS-polyacrylamide gel electrophoresis. The membrane preparations contained three major size classes of polypeptide of 155,000, 62,500 and 43,500 daltons. At least five glycopeptides were separated of which two stained intensely with periodic acid-Schiff reagent, but poorly with coomassie blue. Trypsin hydrolysis of whole cream and isolated milk fat globule membrane revealed major differences in the rates of protein hydrolysis. Many of the membrane proteins of whole cream resisted proteolysis compared with the same proteins in the isolated membrane. Two glycopeptides were resistant to trypsin digestion in either preparation. Treatment of whole cream with neuraminidase led to the release of at least 70% of the protein-bound sialic acid. Whole cream and isolated membrane samples were iodinated with 125I in the presence of lactoperoxidase and hydrogen peroxide. The membrane proteins were significantly more accessible to lactoperoxidase-125I i in isolated membrane compared with the proteins of whole cream. Polypeptides of molecular weight 43,500 and approximately 48,000 daltons were predominantly labelled in whole cream and could be eluted from the fat globules with magnesium chloride (1.5m). The results strongly suggest that the proteins of milk fat globule membrane are asymmetrically arranged in the membrane and that most of the protein-bound sialic acid is present on the external surface of milk fat globules.

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The presence of plasma membrane enzymes on the surface of bovine milk fat globules

Cited by 67 publications

References 8 publications

Plasma Membranes of Mammalian Cells

Plasma Membranes of Mammalian Cells

Enzyme Markers in Characterization of Isolated Plasma Membranes

Studies on the structure of milk fat globule membrane

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