Derivatization of a 5′-(vinylsulfonylaminodeoxy)adenosine scaffold with a clickable functionality provided an activity-based probe that was used to label native carrier protein (CP) motifs in nonribosomal peptide synthetases (NRPSs). When coupled with a fluorescent tag, this probe selectively targeted phosphopantetheinylated CPs (holo-form) from recombinant NRPS enzyme systems and in whole proteomes.