Localization of lysophosphatidylcholine in bovine chromaffin granules

Filgueiras, O. M. de Oliveira; Besselaar, A.M.H.P. van den; Bosch, H. van den

doi:10.1016/0005-2736(79)90316-x

Cited by 24 publications

(2 citation statements)

References 53 publications

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“…Total lipids were extracted (Bligh & Dyer, 1959) from the large granule fraction, and the phospholipid composition was obtained by two-dimensional TLC followed by visualization by iodine vapor and assay of phospholipid phosphorus in the various spots. The composition on a mole percent basis was found to be 8.1% phosphatidylserine, 10.1% lysophosphatidylcholine, 15.1% sphingomyelin, 35.7% phosphatidylethanolamine, and 31% phosphatidylcholine, consistent with literature values (de Oliveira-Filgueiras et al, 1979).…”

Section: Methodssupporting

confidence: 88%

Phospholipids as adjuncts for calcium ion stimulated release of chromaffin granule contents: implications for mechanisms of exocytosis

Nayar¹,

Hope²,

Cullis³

1982

Biochemistry

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Structure-function relationships for the lipid component of chromaffin granules isolated from the bovine adrenal medulla have been investigated by employing 31P nuclear magnetic resonance (NMR), freeze-fracture, and spectrophotometric techniques. Two aspects have been studied in detail, namely, the structural preferences of lipids in the isolated granule membrane and derived liposomal model membrane systems as well as the influence of exogenous lipid (in the form of sonicated vesicle systems) on the Ca2+-stimulated release of granule contents. It is shown that at least 90% of endogenous granule membrane phospholipids assume a liquid-crystalline bilayer configuration at physiological temperatures. Liposomal dispersions of total granule lipid also exhibit bilayer structure, consistent with a structural role of phospholipids in vivo. Incubation of intact isolated granules in the presence of up to 10 mM Ca2+ does not induce significant release of contents above background levels. However, it is shown that incubation of granules in the presence of sonicated phospholipid systems which undergo structural transitions in the presence of Ca2+ can cause immediate and total release of granule contents at Ca2+ levels of 2 mM or more. This behavior is attributed to disruption of granule membrane integrity due to fusion of the vesicle systems with the chromaffin granules. Direct evidence for such fusion is obtained by freeze-fracture electron microscopy. On the basis of this information and with the assumption that the inner leaflet of the adrenal cell plasma membrane is composed predominantly of phosphatidylethanolamine and phosphatidylserine, a mechanism of Ca2+-stimulated exocytotic release of catecholamines in vivo is proposed.

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Section: Methodssupporting

confidence: 88%

Phospholipids as adjuncts for calcium ion stimulated release of chromaffin granule contents: implications for mechanisms of exocytosis

Nayar¹,

Hope²,

Cullis³

1982

Biochemistry

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“…For example, equimolar mixtures of LPC and fatty acids form bilayers, based on which the retardation of haemolysis by such mixtures could be explained. 4a Viability of certain cell types and organelles in the presence of significant concentrations of LPC 16 was attributed to bilayer formation between fatty acid and LPC. 4a Equimolar mixtures of LPC and cholesterol also form a complex and it has been suggested that cholesterol can buffer the membranolytic effect of LPC.…”

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confidence: 99%