The invention generally relates to targeted compounds for the site-specific coupling of chemical moieties. The present invention features a targeted compound for the coupling of chemical moieties comprising at least one targeting domain capable of binding a target, and at least one linking moiety of up to 80 amino acids, preferably alanine, proline, and serine, and at least one coupling site consisting of cysteine or a cysteine-rich peptide motif (CXC, CXXC, or CXXXC), and wherein said linking moiety connects the targeting domain and a coupling site and/or wherein a linking moiety connects two coupling sites. The invention further features fusion proteins with ubiquitin muteins (Affilin ®) as targeting domain. The invention also relates to the use of the targeted compounds for medical applications, in treatment or diagnosis of diseases.
