1. Academic Validation
  2. Recessively inherited L-DOPA-responsive dystonia caused by a point mutation (Q381K) in the tyrosine hydroxylase gene

Recessively inherited L-DOPA-responsive dystonia caused by a point mutation (Q381K) in the tyrosine hydroxylase gene

  • Hum Mol Genet. 1995 Jul;4(7):1209-12. doi: 10.1093/hmg/4.7.1209.
P M Knappskog 1 T Flatmark J Mallet B Lüdecke K Bartholomé
Affiliations

Affiliation

  • 1 Department of Biochemistry and Molecular Biology, University of Bergen, Norway.
Abstract

Tyrosine hydroxylase (TH) catalyzes the conversion of L-tyrosine to L-dihydroxyphenylalanine (L-DOPA), the rate-limiting step in the biosynthesis of dopamine. Recently, we described a point mutation in hTH (Q381K) in a family of two siblings suffering from progressive L-DOPA-responsive dystonia (DRD), representing the first reported mutation in this gene. We here describe the cloning, expression and steady-state kinetic properties of the recombinant mutant Enzyme. When expressed by a coupled in vitro transcription-translation system and in E. coli, the mutant Enzyme represents a kinetic variant form, with a reduced affinity for L-tyrosine. The 'residual activity' of about 15% of the corresponding wild-type hTH (isoform hTH1), at substrate concentrations prevailing in vivo, is compatible with the clinical phenotype of the two Q381K homozygote patients carrying this recessively inherited mutation.

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