Updated project metadata. The isobaric quantitative protein interaction reporter (iqPIR) has now been extended to six channels, enabling quantitation of cross-links from six different samples simultaneously. To analyze data for such cross-linkers, the two-channel mode of quantitative analysis was extended to accommodate any number of channels with defined isotope peak offsets. The HeLa 1:1:1:1:1 data was used for the development of the quantitation method of the 6-plex iqPIR.