1977
DOI: 10.1083/jcb.72.3.617
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Enzymic characteristics of fat globule membranes from bovine colostrum and bovine milk.

Abstract: Fat globule membranes have been isolated from bovine colostrum and bovine milk by the dispersion of the fat in sucrose solutions at 4~ and fractionation by centrifugation through discontinuous sucrose gradients. The morphology and enzymic characteristics of the separated fractions were examined.Fractions comprising a large proportion of the total extracted membrane were thus obtained having high levels of the Golgi marker enzymes UDP-galactose Nacetylglucosamine fl-4-galactosyltransferase and thiamine pyrophos… Show more

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Cited by 43 publications
(9 citation statements)
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References 24 publications
(41 reference statements)
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“…Morphological and biochemical studies of secretion in different cells, including mammary epithelial cells during lactation, provide evidence for a continuous turnover between endomembranes and the plasma membrane segments related to the secretory processes (20). These events could explain the presence of Golgi (24,25,34) and endoplasmic reticulum enzymes (17,25) in MFGM preparations and their phospholipid composition intermediate between that of the Golgi and the plasma membranes (34), even if contami-2 Although clearing of membrane particles was more frequently observed, it may eventually not correspond to the prevalent mechanism if the extrusion without particle segregation is accomplished faster. a The segregation of actin during extrusion is, in view of the particle rearrangements which we observed, a preferable alternative to account for the absence of actin in MFGM preparations.…”
Section: Discussionmentioning
confidence: 99%
See 1 more Smart Citation
“…Morphological and biochemical studies of secretion in different cells, including mammary epithelial cells during lactation, provide evidence for a continuous turnover between endomembranes and the plasma membrane segments related to the secretory processes (20). These events could explain the presence of Golgi (24,25,34) and endoplasmic reticulum enzymes (17,25) in MFGM preparations and their phospholipid composition intermediate between that of the Golgi and the plasma membranes (34), even if contami-2 Although clearing of membrane particles was more frequently observed, it may eventually not correspond to the prevalent mechanism if the extrusion without particle segregation is accomplished faster. a The segregation of actin during extrusion is, in view of the particle rearrangements which we observed, a preferable alternative to account for the absence of actin in MFGM preparations.…”
Section: Discussionmentioning
confidence: 99%
“…However, it has been recently assumed that the overall composition of the MFGM relative to the plasma membrane of the alveolar epithelial cells is not affected (19). Unfortunately, analysis of the apical plasmalemma of the lactating mammary cell is not accessible (34).…”
Section: Discussionmentioning
confidence: 99%
“…This phenomenon probably reflects the cellular sources of these membranes, i.e., Golgi membranes (Powell, Jarlfors, & Brew, 1977), the rough endoplasmic reticulum (RER) (Jarasch, Bruder, Keenan, & Franke, 1977) and plasma membranes (Dowben, Brunner, & Philpott, 1967). A prominent marker of Golgi membranes from bovine mammary gland epithelial cells is galactosyltransferase (Keenan, Morre, & Huang, 1972), which also has high specific activity in the MFGM (Powell et al, 1977). A b-type cytochrome which is specifically associated with the RER in cows has also been identified in MFGM and milk microsomes (Jarasch et al, 1977).…”
Section: Distribution Of Milk Enzymesmentioning
confidence: 94%
“…Thus, if blood serum is a source of a given milk enzyme, it is probably through dedicated transcellular transport systems, such as that responsible for the transfer of immunoglobulins (McManaman & Neville, 2003) The largest group of indigenous milk enzymes is that associated with the MFGM and vesicle membranes (Shahani et al, 1973). This phenomenon probably reflects the cellular sources of these membranes, i.e., Golgi membranes (Powell, Jarlfors, & Brew, 1977), the rough endoplasmic reticulum (RER) (Jarasch, Bruder, Keenan, & Franke, 1977) and plasma membranes (Dowben, Brunner, & Philpott, 1967). A prominent marker of Golgi membranes from bovine mammary gland epithelial cells is galactosyltransferase (Keenan, Morre, & Huang, 1972), which also has high specific activity in the MFGM (Powell et al, 1977).…”
Section: Distribution Of Milk Enzymesmentioning
confidence: 97%
“…It has been suggested or implied by other workers that MFGM originates, at least to a considerable degree, directly from secretory vesicles or Golgi apparatus without first being integrated into apical plasma membrane (24,39,44,46) . Although our results do not exclude the possibility of some contribution from other cell membranes to the formation of MFGM, they appear to strongly favor the concept that apical plasma membrane is the major source of the membrane complex enveloping the milk lipid globules .…”
Section: Electron Microscopymentioning
confidence: 97%