MetaCyc Enzyme: homogentisate phytyltransferase

Gene: HPT1 Accession Number: AT2G18950 (MetaCyc)

Synonyms: TPT1, At2g18950, VTE2

Species: Arabidopsis thaliana col

Over-expression of AtHPT (the gene encoding homogentisate phytyltransferase) in leaves and seeds of Arabidopsis increased tocopherol level in both tissues. It indicates that HPT activity is limiting for tocopherol biosynthesis in Arabidopsis [Collakova03].

Locations: chloroplast

Unification Links: TAIR:At2g18950

Relationship Links: Entrez-Nucleotide:PART-OF:AF324344

Gene-Reaction Schematic: ?

Gene-Reaction Schematic

GO Terms:

Cellular Component: GO:0009507 - chloroplast [Collakova01]

Enzymatic reaction of: homogentisate phytyltransferase

EC Number:

phytyl diphosphate + homogentisate + H+ <=> 2-methyl-6-phytyl-1,4-benzoquinol + CO2 + diphosphate

The reaction direction shown, that is, A + B ↔ C + D versus C + D ↔ A + B, is in accordance with the Enzyme Commission system.

The reaction is favored in the direction shown.

In Pathways: vitamin E biosynthesis (tocopherols)


Collakova01: Collakova E, DellaPenna D (2001). "Isolation and functional analysis of homogentisate phytyltransferase from Synechocystis sp. PCC 6803 and Arabidopsis." Plant Physiol 127(3);1113-24. PMID: 11706191

Collakova03: Collakova E, DellaPenna D (2003). "Homogentisate phytyltransferase activity is limiting for tocopherol biosynthesis in Arabidopsis." Plant Physiol 131(2);632-42. PMID: 12586887

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Please cite the following article in publications resulting from the use of MetaCyc: Caspi et al, Nucleic Acids Research 42:D459-D471 2014
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