Geranyl pyrophosphate is an intermediate in isoprenoid biosynthesis formed by joining dimethylallyl pyrophosphate (DPP) with isopentenyl pyrophosphate (IPP), as follows:

DPP + IPP <=> Geranyl Pyrophosphate + PPi (Figure 19.20)

In cholesterol biosynthesis, geranyl pyrophosphate is converted to farnesyl pyrophosphate, as follows:

Geranyl Pyrophosphate + IPP <=> Farnesyl Pyrophosphate + PPi (Figure 19.20)