Site-directed mutagenesis of K396R of the 65 kDa glutamic acid decarboxylase active site obliterates enzyme activity but not antibody binding

Research output: Contribution to journalArticle


The role of K396 in the enzymatic catalysis and the antigenicity of the 65 kDa isoform of glutamate decarboxylase (GAD65) was analyzed using the K396R GAD65 mutant. GAD65 is a major autoantigen in Type 1 diabetes and autoantibodies directed to GAD65 are widely used markers for this disease. We found that (1) recombinant human GAD65 is fully enzymatically active; (2) the K396R mutation abolished GAD65 activity; and (3) the K396R mutant retained full antigenicity to GAD65 autoantibodies in serum from Type 1 diabetes patients, but not to polyclonal antibodies raised to the catalytic domain.


  • Christiane S Hampe
  • Lisa P Hammerle
  • Alberto Falorni
  • John D. Robertson
  • Åke Lernmark
External organisations
  • University of Washington
Research areas and keywords


  • Autoimmunity, Diabetes, Glutamate decarboxylase, Pyridoxal 5-phosphate
Original languageEnglish
Pages (from-to)185-189
Number of pages5
JournalFEBS Letters
Issue number3
Publication statusPublished - 2001 Jan 19
Publication categoryResearch
Externally publishedYes