Supplementary Information
Molecular Lipidomics of Exosomes Released by PC-3 Prostate Cancer CellsAlicia Llorente, Tore Skotland, Tuulia Sylvänne, Dimple Kauhanen, Tomasz Róg, Adam Orłowski, Ilpo Vattulainen, Kim Ekroos, Kirsten Sandvig
This file includes
Calculations related to manuscript section 3.3
Figs. S1 and S2
Table S1 has been loaded separately
Calculations related to manuscript section 3.3
Based on our lipidomics analyses (Table S1), the very long N-amidated species (C24 or C26) of the measured sphingolipids constitute approximately 7.7% of the lipids in the exosomes, whereas PS 18:0/18:1 and PE 18:0/18:1 make up approximately 4.4% and 1.0% respectively. When considering the interaction between lipids in the inner and outer leaflet of the exosomes, one has to take into consideration that the outer leaflet has a larger surface area and will accommodate more lipid molecules than the inner leaflet. In particular, a vesicle with a diameter of 70 nm (the mean size of exosomes with a size distribution of 40-100 nm (see for example reference 3 in manuscript Bobrie et al, Traffic 12 (2001), 1659) and a membrane thickness of 5 nm has an outer surface that is 36% larger than the inner surface. It can then be calculated that PS 18:0/18:1 in the inner leaflet can occupy approximately 80% of the area occupied by the long chain sphingolipids in the outer leaflet, or approximately 95% if we also include PE 18:0/18:1. The PI and DAG species described in the main text are so minor that they contribute very little to such calculations.
Supplementary figures
Fig. S1. Lipid structures, lipid abbreviations and examples of lipid fragmentation by mass spectrometry. A-Lipid abbreviations are shown. B-Structure of cholesterol and structure and fragmentation spectra of PS 18:0/18:1 (m/z 788.6 [M-H]-, CE; 40 eV) and SM d18:1/24:0 (m/z 815.6 [M+H]+, CE; 35 eV) by electrospray ionization tandem mass spectrometry (ESI-MS/MS) obtained from PC-3 cells is shown.
Fig. S2. Chain length of fatty acyl groups in exosomes and PC-3 cells lipids. Mol% of lipids with a specific number of carbon atoms in the fatty acyl groups is shown for the four main lipid classes. A. PC; B. PE; C. PS; D. SM.
Fig S1. Lipid structures and abbreviations and examples of lipid fragmentation by mass spectrometry.
Fig. S2. Chain length of fatty acyl groups in exosomes and PC-3 cells lipids.
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