Table 1.
Elution time and parent ion masses of candidate glycerophosphocholine species bound to proteins in dialyzed α-synuclein KO cytosolic extracts identified by LC-ESI-MS
| Parent ion mass (± 0.15 m/z)a | LC elution time (± 0.4 min)a | Lipid species in complex with proteins in KO cytosolb | Species abundance relative to Wt (Fold change) | Species bound to α-syn following immunoprecipitation (Fold change above non-specific binding)c |
| 494.7 | 12.29 | C14:1-PAF | ↑-fold | |
| 12.89 | C16:1-LPC | No change | ||
| 496.8 | 13.79 | C14:0-PAF | ↑3-fold | ↑9.2x |
| 14.39 | C16:0 LPC | ↑2-fold | ↑9.8y | |
| 520.7 | 13 | C16:2-PAF | ↑2-fold | |
| 13.41 | C18:2-LPC | No change | ||
| 522.8 | 14.66 | C16:1-PAF | ↑5-fold | |
| 15.15 | C18:1-LPC | ↑2-fold | ||
| 524.9 | 17.2 | C16:0-PAFc | ↑2-fold | ↑1.7x |
| 18.11 | C18:0-LPC | ↑4-fold | ↑2.3y | |
| 545 | C18:4-PAF | ↑11-fold | ||
| 13.12 | C20:4-LPC | |||
| 545.9 | 13.11 | C18:3-PAF | De novo detection | |
| 13.99 | C20:3-LPC | |||
| 568.8 | 13.12 | C20:6-PAF | ↑4-fold | |
| C22:6-LPC | ||||
| 581 | 15.32 | C20:0-PAF | ↑17-fold | |
| 16.04 | C22:0-LPC | ↑12-fold | ||
| 594 | 16.52 | C24:7-LPC | ↑2-fold | |
| C22:7-PAF | ||||
| 23:7c | ||||
| 24:7d | ||||
| C20:0-acyl-PAF | ||||
| C24:0-lysoPAF |
a Variations between m/z and retention time between runs were established for all glycerophospholipid species and respresents mean ± standard deviation.
b Identification is predicted based on the theoretical monoisotopic mass values. CX:Y refers to the number of carbon atoms and double bonds in the sn-1 chain with a predicted acetyl (PAF) or hydroxyl (LPC) group at the sn-2 position. Only the most likely species are indicated although multiple isoforms may be present with the double bond in the alkyl chain at different positions. Isobaric species with same m/z eluting at different times were not further distinguished with the exception of C16:0 PAF.
c Replicate experiments were performed in which α-syn was immunoprecipitated from Wt cytosolx or recombinant α-syn was added to KO cytosoly. Immunoprecipitates were analysed by LC-ESI-MS. Data represent mean increase in relative abundance above background (non-specific) signal ± standard deviation as described in Materials and Methods.
d Identity verified by based on its coelution with d4-C16-PAF spiked at time of analysis.