SUBSTRATE SPECIFICITIES
      TyrA Nomenclature
      Current Specificity Tabulations
      TyrA Supradomains &
          Supradomain Segements
  CURATED SEQUENCES
      TyrA
  GENE FUSIONS
      TyrA
  TyrA-NULL GENOMES
      tyrA-null Genomes
      tyrA Pseudogenes
  REGULATION
      Attenuation
  ORGANISMS
      Key to Acronyms
      Lookup Tool
  PHYLO-PURITY OF TyrPath
      Cohesion Groups
      TyrPath Mosaics
  TOOLS
      Interactive Alignment
      AroBlast Search
      Specificity Predictor
      16S rRNA Trees
  REFERENCES


Tyrosine Biosynthesis Pathways

TyrPath is dedicated to the analysis of the specific branch leading from prephenate to L-tyrosine (Pathway Maps). The reactions utilize aminotransferase and dehydrogenase steps. Depending upon the order of these two reactions, either 4-hydroxyphenylpyruvate or L-arogenate is deployed as a unique intermediate. Specificity for the cyclohexadienyl substrate (prephenate or L-arogenate) can be narrow or broad. Specificity for the pyridine nucleotide substrate can also be narrow or broad. Much of TyrPath is devoted to consideration of patterns of substrate specificity.

At the present time TyrPath is restricted to the TyrA dehydrogenases. Inclusion of the tyrosine-pathway aminotransferase is a challenging undertaking that will be coordinated with analysis of the PhePath segment of biosynthesis. This is because the tyrosine-pathway aminotransferase is usually also functional as a phenylalanine-pathway aminotransferase. The complexity to be dealt with is that that at least three homology types function as primary aromatic aminotransferases in different organisms. In addition, there is functional overlap where a given aminotransferase may participate in more than one pathway, e.g., aromatic and histidine biosynthesis. On the other hand, a multiplicity of aminotransferases may contribute aminotransferase function within a single pathway (Jensen & Gu, 1996).

The sidebar links facilitate direct navigation to all of the analysis, curated sequences, and tools that are relevant to the tyrosine branch of biosynthesis (TyrPath).



L O S   A L A M O S   N A T I O N A L   L A B O R A T O R Y • Est 1943
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