Example MSnExp and MSnSet data sets

itraqdata is and example data sets is an iTRAQ 4-plex experiment that has been run on an Orbitrap Velos instrument. It includes identification data in the feature data slot obtain from the Mascot search engine. It is a subset of an spike-in experiment where proteins have spiked in an Erwinia background, as described in

Karp et al. (2010), Addressing accuracy and precision issues in iTRAQ quantitation, Mol Cell Proteomics. 2010 Sep;9(9):1885-97. Epub 2010 Apr 10. (PMID 20382981).

The spiked-in proteins in itradata are BSA and ENO and are present in relative abundances 1, 2.5, 5, 10 and 10, 5, 2.5, 1 in the 114, 115, 116 and 117 reporter tags.

The msnset object is produced by running the quantify method on the itraqdata experimental data, as detailed in the quantify example. This example data set is used in the MSnbase-demo vignette, available with vignette("MSnbase-demo", package="MSnbase").

The msnset2 object is another example iTRAQ4 data that is used to demonstrate features of the package, in particular the iPQF feature aggregation method, described in iPQF. It corresponds to 11 proteins with spectra measurements from the original data set described by Breitwieser et al. (2011) General statistical modeling of data from protein relative expression isobaric tags. J. Proteome Res., 10, 2758-2766.

itraqdata

Examples

data(itraqdata)
itraqdata
#> MSn experiment data ("MSnExp")
#> Object size in memory: 1.9 Mb
#> - - - Spectra data - - -
#>  MS level(s): 2 
#>  Number of spectra: 55 
#>  MSn retention times: 19:09 - 50:18 minutes
#> - - - Processing information - - -
#> Data loaded: Wed May 11 18:54:39 2011 
#> Updated from version 0.3.0 to 0.3.1 [Fri Jul  8 20:23:25 2016] 
#>  MSnbase version: 1.1.22 
#> - - - Meta data  - - -
#> phenoData
#>   rowNames: 1
#>   varLabels: sampleNames sampleNumbers
#>   varMetadata: labelDescription
#> Loaded from:
#>   dummyiTRAQ.mzXML 
#> protocolData: none
#> featureData
#>   featureNames: X1 X10 ... X9 (55 total)
#>   fvarLabels: spectrum ProteinAccession ProteinDescription
#>     PeptideSequence
#>   fvarMetadata: labelDescription
#> experimentData: use 'experimentData(object)'

## created by
## msnset <- quantify(itraqdata, method = "trap", reporters = iTRAQ4)
data(msnset)
msnset
#> MSnSet (storageMode: lockedEnvironment)
#> assayData: 55 features, 4 samples 
#>   element names: exprs 
#> protocolData: none
#> phenoData
#>   sampleNames: iTRAQ4.114 iTRAQ4.115 iTRAQ4.116 iTRAQ4.117
#>   varLabels: mz reporters
#>   varMetadata: labelDescription
#> featureData
#>   featureNames: X1 X10 ... X9 (55 total)
#>   fvarLabels: spectrum ProteinAccession ... collision.energy (15 total)
#>   fvarMetadata: labelDescription
#> experimentData: use 'experimentData(object)'
#> Annotation: No annotation 
#> - - - Processing information - - -
#> Data loaded: Wed May 11 18:54:39 2011 
#> iTRAQ4 quantification by trapezoidation: Wed Apr  1 21:41:53 2015 
#>  MSnbase version: 1.1.22 

data(msnset2)
msnset2
#> MSnSet (storageMode: lockedEnvironment)
#> assayData: 614 features, 4 samples 
#>   element names: exprs 
#> protocolData: none
#> phenoData: none
#> featureData
#>   featureNames: 11695 11696 ... 390 (614 total)
#>   fvarLabels: accession sequence ... rudist.org (9 total)
#>   fvarMetadata: labelDescription
#> experimentData: use 'experimentData(object)'
#> Annotation:  
#> - - - Processing information - - -
#> Subset [13758,4][614,4] Mon Jun 15 21:03:40 2015 
#>  MSnbase version: 1.14.1