Protein identification in mass-spectrometry imaging

With a rapidly growing number of biomedical applications of mass-spectrometry imaging (MSI) and expansion of the technique into the clinic, spectrum annotation is an increasingly pressing issue in MSI. Although identification of the species of interest is the key to answering biomedical research questions, only few of the hundreds of observed biomolecular signals in each MSI spectrum can be easily identified or interpreted. So far, no standardized protocols resolve this issue.Present strategies for protein identification in MSI, their limitations and future developments are the scope of this review. We discuss advances in MSI technology, workflows and bioinformatic tools to improve the confidence and the number of protein identifications within MSI studies.

► Trends in protein-identification strategies in mass-spectrometry imaging (MSI).
► Compare and contrast direct versus indirect techniques for protein identification.
► Imaging protein-identification workflows.