Updated project metadata. To identify relevant substrates for meprin α/β heterodimers, we applied mass spectrometry-based N-terminomics of mouse colon tissue as well as of human Caco-2 cells and identified galectin-3 as a novel intestinal substrate. The proteolytic processing of galectin-3 by meprin α/β heterodimers plays a key role in the maintenance of the host-microbiome homeostasis within the colon.