| Autor: |
Palestini P; Department of Medical Chemistry and Biochemistry, Medical School, University of Milan, Italy., Allietta M, Sonnino S, Tettamanti G, Thompson TE, Tillack TW |
| Jazyk: |
angličtina |
| Zdroj: |
Biochimica et biophysica acta [Biochim Biophys Acta] 1995 May 04; Vol. 1235 (2), pp. 221-30. |
| DOI: |
10.1016/0005-2736(95)80008-4 |
| Abstrakt: |
In two-component phosphatidylcholine bilayers with coexisting liquid and P beta' gel phases, the distribution between phases of low concentrations of glycosphingolipids can be determined by freeze-etch electron microscopy after labeling the glycolipid with a suitable protein. We have found that the distribution depends upon the glycosphingolipid species (Rock, P. et al., (1991) Biochemistry 30, 19-25). Using this technique with cholera toxin as the protein label and bilayers formed from dipalmitoyl- and dielaidoylphosphatidylcholine (1:1) containing < 1 mol% GM1, we have studied the distribution of a family of GM1 homologues differing in the acyl chain and sphingoid base moieties. The GM1 preference for the P beta' ripple phase decreases with decreasing acyl chain length and increasing unsaturation. GM1 with either a C18:1 or C20:1 sphingoid base shows similar distributions in liquid and gel phases. When the molecules are preferentially found in the P beta' phase, they are positioned along unique loci in both A and A/2 forms of the ripple structure. This localization and acyl chain dependence reflect the volume, shape and localization of molecular packing defects in the P beta' phase. The ganglioside inclusions stabilize the P beta' phase and form compositional domains of unique topography. |
| Databáze: |
MEDLINE |
| Externí odkaz: |
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