Pyruvate and glyceraldehyde 3-phosphate are converted by DOXP synthase (Dxs) to 1-deoxy-D-xylulose 5-phosphate, and by DOXP reductase (Dxr, IspC) to 2- C -methyl-D-erythritol 4-phosphate (MEP). The subsequent three reaction steps catalyzed by 4-diphosphocytidyl-2- C -methyl-D-erythritol synthase (YgbP, IspD), 4-diphosphocytidyl-2- C -methyl-D-erythritol kinase (YchB, IspE), and 2- C -methyl-D-erythritol 2,4-cyclodiphosphate synthase (YgbB, IspF) mediate the formation of 2- C -methyl-D-erythritol 2,4-cyclopyrophosphate (MEcPP). Finally, MEcPP is converted to ( E )-4-hydroxy-3-methyl-but-2-enyl pyrophosphate ( HMB-PP ) by HMB-PP synthase (GcpE, IspG), and HMB-PP is converted to isopentenyl pyrophosphate (IPP) and dimethylallyl pyrophosphate (DMAPP) by HMB-PP reductase (LytB, IspH).
Tubang-bakod is a smooth, glabrous, erect, branched shrub 2 to 5 meters high. Branches are stout, cylindric, and green. Leaves are entire, orbicular-ovate, angular or somewhat 3- to 5-lobed, 10 to 18 centimeters long, acuminate with a cordate base. Petioles are long. Flowers are greenish or greenish-white, unisexual, 7 to 8 millimeters in diameter, borne on axillary cymes, the staminate ones villous inside, the petals reflexed. Stamens are10, the filaments of the inner 5, connate. Fruits are capsules, at first fleshy, becoming dry, rounded, with 2 to 3 one-seeded divisions, 3 to 4 centimeters long.