It has been noted  that only a handful of a protein’s possible tryptic peptides are consistently observed in proteomics experiments. We denote these consistently observed peptides to be proteotypic peptides. Such peptides have a variety of potential applications in proteomic research including improving protein identification scoring functions of database search software, providing a panel of reagents for protein quantification as well as the annotation of genomes for coding sequences of e.g.
Corra is a single, user-friendly, informatic framework, that is simple to use and fully customizable, for the enabling of LC-MS-based quantitative proteomic workflows of any size, able to guide the user seamlessly from MS data generation, through data processing, visualization, and statistical analysis steps, to the identification of differentially abundant or expressed candidate features for prioritized targeted identification by subsequent MS/MS.
As a complement to the well-established discovery proteomic methods, targeted mass spectrometry based on SRM is becoming an important tool for the generation of reproducible, sensitive and quantitatively accurate data from biological samples.
Unipep is a project to provide access to proteomics data from the Serum Biomarker group at the Swiss Federal Institute of Technology (ETH) in Zurich Switzerland, and the Institute for Systems Biology (ISB) in Seattle, Washington USA.
PhospoPep version 2.0 is a project to support systems biology signaling research by providing interactive interrogation of MS-derived phosphorylation data from 4 different organisms. Currently there is data from the fly (Drosophila melanogaster), human (Homo sapiens), worm (Caenorhabditis elegans), and yeast (Saccharomyces cerevisiae).
The PeptideAtlas SRM Experiment Library (PASSEL) is a component of the PeptideAtlas project that is designed to enable submission, dissemination, and reuse of SRM experimental results from analysis of biological samples.
The SRMAtlas is a compendium of targeted proteomics assays to detect and quantify proteins in complex proteome digests by mass spectrometry. It results from high-quality measurements of natural and synthetic peptides conducted on a triple quadrupole mass spectrometer, and is intended as a resource for selected/multiple reaction monitoring (SRM/MRM)-based proteomic workflows.
Libra is a module within the trans-proteomic pipeline to perform quantification on MS/MS spectra that have isobaric multi-reagent labeled peptides. More specifically, at ISB we use Libra on MS/MS spectra of iTRAQ labeled samples; it can also be used on TMT labeled samples. There is no limitation to the number of channels that Libra can quantitate against.