Catalyzes the transfer of a geranyl-geranyl moiety from geranyl-geranyl pyrophosphate to a cysteine at the fourth position from the C-terminus of proteins having the C-terminal sequence Cys-aliphatic-aliphatic-X (CaaX). Seems to exclusively prenylate CaaX substrates with leucine in the terminal position. The beta subunit is responsible for peptide-binding. May negatively regulate abscisic acid (ABA) signaling in guard cells and auxin-induced lateral root initiation. Negatively regulates ABA signaling in guard cells. in negative regulation of auxin-induced lateral root initiation. geranylgeranyl diphosphate + L-cysteinyl-[protein] = diphosphate + S-geranylgeranyl-L-cysteinyl-[protein] Binds 1 zinc ion per subunit. kcat is 0.5 h(-1), 0.08 h(-1), 0.008 h(-1) and 0.012 h(-1) for CVIL, CVII, CVIQ and CVIM substrates, respectively. Optimum pH is 7.9-8.5 for CTIL substrate. Optimum temperature is 30-37 degrees Celsius for CTIL substrate. Heterodimer of an alpha and a beta subunit. Expressed in roots, leaves, stems, flowers and siliques. No visible phenotype under normal growth conditions, but mutant plants have an enhanced response to abscisic acid (ABA)-mediated stomatal closure and increased lateral root formation in response to exogenous auxin. Belongs to the protein prenyltransferase subunit beta family.