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expand all sections collapse all sections Oryza sativa gene "flo4" (GR:0101188)
Species Oryza sativa (Rice) [ GR_tax:013681 ]
Accession GR:0101188
Gene Symbol flo4
Gene Name floury endosperm 4 
Synonyms (9)
E.C. Numbers (1) 2.7.9.1
Pathway Reactions (1) Pyruvate,phosphate dikinase
Chromosome No. 5
Gene Type CDS (Protein coding)
Has Phenotype yes
Description Pyruvate orthophosphate dikinase (PPDK; EC 2.7.9.1) catalyzes the interconversion of pyruvate, ATP, and Pi (inorganic Phosphate) with phosphoenolpyruvate (PEP), AMP, and PPi. This enzyme plays an important role in the photosynthesis of C4 and crassulacean acid metabolism (CAM) plants, where it catalyzes the conversion of pyruvate to PEP. Although PPDK is also present in C3 plants such as rice, it is not thought to participate directly in photosynthesis. Nevertheless, the PPDK found in C3 plants is highly homologous to the C4 enzyme with regard to its structure and biochemical characteristics. The mutant form results in white-core opaque phenotype. The gene flo4, cosegregates with insertional mutations in the OsPPDKB rice gene. flo4 is an important modulator of carbon flow for starch and lipid biosynthesis during grain filling. There are two promoters for this gene. One gives a long form of the transcript (3.4kb) that encodes for the PPDK protein targeted to the plastid. Another promoter found in the second intron of the larger 3.4kb transcript region of the gene, gives a shorter form of the transcript (3.0kb) and the translated PPDK protein is targeted to cytoplasm, because the translational start site of the smaller 3.0kb form is present downsteram of the plastid targeting peptide found in the long form. The plastid form is expressed in the leaf blade and sheath, wheras the cytosolic form was detected in root, leaf blade, leaf sheath and developing grains and was not expressed in carpels. The cytosolic form was induced after pollination and gradually increased during fruit (grain) development.
Curator Comment Since there are two different promoters and translation start sites that give rise to the cytosolic and plastid forms, this locus must be split into two different loci. One for plastid and another for cytosolic forms.
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