Method of producing an immunoligand/payload conjugate

An immunoligand/payload conjugate comprising

• a) an immunoligand selected from the group consisting of one or more of:
• i) an antibody,
• ii) an antibody-based binding protein being a protein containing at least one antibody-derived VH, VL, or CH immunoglobulin domain,
• iii) an antibody fragment binding to a receptor, antigen, growth factor, cytokine, or hormone, or
• iv) an antibody mimetic selected from the group consisting of DARPins, C-type lectins, A-domain proteins of S. aureus, transferrins, lipocalins, 10th type Ill domains of fibronectin, Kunitz domain protease inhibitors, affilins, gamma crystallin derived binders, cysteine knots or knottins, thioredoxin A scaffold based binders, nucleic acid aptamers, artificial antibodies produced by molecular imprinting of polymers, and stradobodies,
• b) at least one payload having a molecular weight not exceeding 2,500 Dalton, and
• c) a linker conjugating the immunoligand of (a) or a subunit thereof to the payload, said linker comprising a sortase recognition motif having its C-terminal amino acid replaced with a Glyn, wherein n>1.