Proteomic Profiling of Detergent Resistant Membranes (Lipid Rafts) of Prostasomes.
Prostasomes are exosomes derived from prostate epithelial cells through exocytosis by multivesicular bodies. Prostasomes have a bilayered membrane and readily interact with sperm. The membrane lipid composition is unusual with a high contribution of sphingomyelin at the expense of phosphatidylcholine and saturated and monounsaturated fatty acids are dominant. Lipid rafts are liquid-ordered domains that are more tightly packed than the surrounding nonraft phase of the bilayer. Lipid rafts are proposed to be highly dynamic, submicroscopic assemblies that float freely within the liquid disordered membrane bilayer and some proteins preferentially partition into the ordered raft domains. We asked the question whether lipid rafts do exist in prostasomes and, if so, which proteins might be associated with them. Prostasomes of density range 1.13-1.19g/ml were subjected to density gradient ultracentrifugation in sucrose fabricated by phosphate buffered saline (PBS) containing 1% Triton X-100 with capacity for banding at 1.10 g/ml, i.e. the classical density of lipid rafts. Prepared prostasomal lipid rafts (by gradient ultracentrifugation) were analyzed by mass spectrometry. The clearly visible band on top of 1.10g/ml sucrose in the Triton X-100 containing gradient was subjected to liquid chromatography-tandem MS and more than 370 lipid raft associated proteins were identified. Several of them were involved in intraluminal vesicle formation, e.g. tetraspanins, ESCRTs, and Ras-related proteins. This is the first comprehensive liquid chromatography-tandem MS profiling of proteins in lipid rafts derived from exosomes. Data are available via ProteomeXchange with identifier PXD002163.
From the ‡Department of Medical Sciences, Uppsala University, 75185 Uppsala, Sweden;
Louise
L
Dubois
From the ‡Department of Medical Sciences, Uppsala University, 75185 Uppsala, Sweden; goran.ronquist@medsci.uu.se.
Karl K Göran
KK
Ronquist
§Department of Analytical Chemistry, Science for Life Laboratory, Uppsala University, 751 24 Uppsala, Sweden.
Bo
B
Ek
From the ‡Department of Medical Sciences, Uppsala University, 75185 Uppsala, Sweden;
Gunnar
G
Ronquist
From the ‡Department of Medical Sciences, Uppsala University, 75185 Uppsala, Sweden;
Anders
A
Larsson
D002499:Centrifugation, Density Gradient; D002853:Chromatography, Liquid; D003902:Detergents / Q000737:chemistry; D056827:Endosomal Sorting Complexes Required for Transport / Q000737:chemistry / Q000302:isolation & purification; D055354:Exosomes / Q000737:chemistry* / Q000378:metabolism; D006801:Humans; D008055:Lipids / Q000737:chemistry / Q000302:isolation & purification; D059627:Liquid Phase Microextraction / Q000379:methods*; D008297:Male; D013058:Mass Spectrometry; D021962:Membrane Microdomains / Q000737:chemistry* / Q000378:metabolism; D058977:Molecular Sequence Annotation; D017830:Octoxynol / Q000737:chemistry; D011467:Prostate / Q000737:chemistry* / Q000378:metabolism; D020543:Proteome / Q000737:chemistry / Q000302:isolation & purification*; D059470:Tetraspanins / Q000737:chemistry / Q000302:isolation & purification; D018631:ras Proteins / Q000737:chemistry / Q000302:isolation & purification
D003902:Detergents; D056827:Endosomal Sorting Complexes Required for Transport; D008055:Lipids; D020543:Proteome; D059470:Tetraspanins; D017830:Octoxynol; D018631:ras Proteins