Updated project metadata. Chemical cross-linking coupled to mass spectrometry was used to study binary and ternary complexes involving cyclin-dependent kinase 8 (CDK8), cyclin-C, and subunit 12 of the Mediator complex (MED12). Cross-linking was performed using different cross-linking chemistries: (1) disuccinimidyl suberate (DSS); (2) a combination of pimelic acid dihydrazide (PDH) and the coupling reagent, DMTMM.