The enzyme, found in plants and cyanobacteria, catalyses the final step in the biosynthesis of phylloquinone (vitamin K1), an electron carrier associated with photosystem I. The enzyme is specific for the quinol form of the substrate, and does not act on the quinone form .
Sakuragi Y, Zybailov B, Shen G, Jones AD, Chitnis PR, van der Est A, Bittl R, Zech S, Stehlik D, Golbeck JH, Bryant DA
Insertional inactivation of the menG gene, encoding 2-phytyl-1,4-naphthoquinone methyltransferase of Synechocystis sp. PCC 6803, results in the incorporation of 2-phytyl-1,4-naphthoquinone into the A(1) site and alteration of the equilibrium constant between A(1) and F(X) in photosystem I.