About MSIPep

MSIPep is a curated database of peptides identified in matrix-assisted laser desorption/ionization mass spectrometry imaging (MALDI-MSI) experiments. It collects peptide observations reported in the literature from 2008 onwards. Each entry records the measured m/z, the parent protein, the tissue and species, and the source publication.

What is in the database

Each observation is one peptide reported at one m/z in one experiment, meaning one publication, species and tissue. The same peptide reported by two studies appears as two observations, so you can compare evidence across studies.

Quality control

• Theoretical m/z values are recalculated from the sequence, modifications, charge and adduct using monoisotopic residue masses and Unimod modification masses. They are not copied from the source.
• The measured m/z is compared with the calculated value, and entries outside the tolerance are flagged.
• Each peptide is checked against the UniProt sequence of its protein, and each protein against the experiment's species.
• Flagged entries are reviewed by a curator against the original publication. Until then they are shown with a Needs review label.

Standards

Peptides with modifications are written in ProForma 2.0. Proteins use UniProt accessions, species use NCBI Taxonomy IDs, and tissues use UBERON anatomy terms.

Licence

MSIPep data are released under CC BY 4.0. Please cite MSIPep and the original publications.