Accepted name: all-trans-nonaprenyl diphosphate synthase [geranylgeranyl-diphosphate specific]
Reaction: geranylgeranyl diphosphate + 5 isopentenyl diphosphate = 5 diphosphate + all-trans-nonaprenyl diphosphate
Glossary: solanesyl diphosphate = all-trans-nonaprenyll diphosphate
Other name(s): nonaprenyl diphosphate synthase (ambiguous); solanesyl diphosphate synthase (ambiguous); At-SPS2; At-SPS1; SPS1; SPS2
Systematic name: geranylgeranyl-diphosphate:isopentenyl-diphosphate transtransferase (adding 5 isopentenyl units)
Comments: Geranylgeranyl diphosphate is preferred over farnesyl diphosphate as allylic substrate [1]. The plant Arabidopsis thaliana has two different enzymes that catalyse this reaction. SPS1 contributes to the biosynthesis of the ubiquinone side-chain while SPS2 supplies the precursor of the plastoquinone side-chains [2].
1.  Hirooka, K., Bamba, T., Fukusaki, E. and Kobayashi, A. Cloning and kinetic characterization of Arabidopsis thaliana solanesyl diphosphate synthase. Biochem. J. 370 (2003) 679–686. [PMID: 12437513]
2.  Hirooka, K., Izumi, Y., An, C.I., Nakazawa, Y., Fukusaki, E. and Kobayashi, A. Functional analysis of two solanesyl diphosphate synthases from Arabidopsis thaliana. Biosci. Biotechnol. Biochem. 69 (2005) 592–601. [PMID: 15784989]
3.  Jun, L., Saiki, R., Tatsumi, K., Nakagawa, T. and Kawamukai, M. Identification and subcellular localization of two solanesyl diphosphate synthases from Arabidopsis thaliana. Plant Cell Physiol. 45 (2004) 1882–1888. [PMID: 15653808]
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