Calmodulin as a versatile tag for antibody fragments

Dario Neri, Claudia De Lalla, Heike Petrul, Paolo Neri, Greg Winter

Research output: Contribution to journalArticlepeer-review


Calmodulin is a highly acidic protein (net charge -24 at pH 8.0 in the absence of calcium) that binds to peptide and organic ligands with high affinity (Ka>109 M-1) in a calcium-dependent manner. We have exploited these properties to develop calmodulin as a versatile tag for antibody fragments. Fusions of calmodulin with single chain Fv fragments (scFv) could be expressed by secretion from bacteria in good yield (5-15 mg/l in shaker flasks), and purified from periplasmic lysates or broth to homogeneity in a single step, either by binding to anion-exchange resin (DEAE-Sephadex), or to an organic ligand of calmodulin (N-(6-aminohexyl)-5-chloro-1-naphthalenesulfonamide-agarose). The antibody fusions could be detected by binding of fluorescently labeled peptide ligands, as illustrated by their use in confocal microscopy, fluorescent activated cell sorting and "band shift" gel electrophoresis. Moreover, the interaction between calmodulin and peptide ligands could provide a means of heterodimerization of proteins, as illustrated by the assembly of an antibody-calmodulin fusion with maltose binding protein tagged with a peptide ligand of calmodulin.

Original languageEnglish
Pages (from-to)373-377
Number of pages5
JournalNature Biotechnology
Issue number4
Publication statusPublished - 1995

ASJC Scopus subject areas

  • Microbiology
  • Biotechnology


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