Table 1. Known prenylations involved in IDT biosynthetic pathways. Prenyl groups are highlighted in blue. R and R1 on the top white structure indicate locations where the ‘terpenoid’ component of IDTs attaches to the indole component. Prenylations have been grouped by the region of the IDT they prenylate (i.e. ‘indole’ or ‘terpenoid’ component), degree of prenylation (i.e. mono- or bisprenylation), and prenylation mode (i.e. ‘head’ or ‘tail’ isoprenoid condensation). Carbon numbering is based on the conventional IDT numbering scheme. When comparing IDTs to non-IDTs decorated by aromatic PTs, C1,2,3 = C1,2,3; C20 = C4; C21 = C5; C22 = C6 and C23 = C7.