Figure 1. Schematic diagram of reaction catalyzed by HCT in monolignol biosynthesis pathway.

R=Shikimate. 4CL, 4-coumarate-CoA ligase; C3H, p- coumarate 3-hydroxylase; HCT, Hydroxycinnamoyl-CoA: shikimate hydroxycinnamoyl transferase. Compounds in red shadow are precursors for H units and in green shadow are for G and S units.