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

  • Christiane S Hampe
  • Lisa P Hammerle
  • Alberto Falorni
  • John D. Robertson
  • Åke Lernmark
Publishing year: 2001-01-19
Language: English
Pages: 185-189
Publication/Series: FEBS Letters
Volume: 488
Issue: 3
Document type: Journal article
Publisher: Wiley-Blackwell

Abstract english

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.


  • Autoimmunity
  • Diabetes
  • Glutamate decarboxylase
  • Pyridoxal 5-phosphate


  • ISSN: 0014-5793
E-mail: ake [dot] lernmark [at] med [dot] lu [dot] se

Principal investigator

Diabetes and Celiac Unit

+46 40 39 19 01

+46 70 616 47 79


Jan Waldenströms gata 35, Malmö


Lund University Diabetes Centre, CRC, SUS Malmö, Jan Waldenströms gata 35, House 91:12. SE-214 28 Malmö. Telephone: +46 40 39 10 00