Prenyltransferase that attaches isoprenoid moieties to carbon atoms of aromatic substrates in an enzyme-catalyzed Friedel-Crafts reaction (PubMed:20351110). Shows specificity for dimethylallyl diphosphate (DMAPP) and does not accept geranyl diphosphate (GPP) or isopentenyl diphosphate (IPP) (PubMed:20351110). Prenylates the artificial substrate 2,7-dihydroxynaphthalene (2,7-DHN), as well as dihydrophenazine-1-carboxylic acid and 4-hydroxybenzoic acid at lower levels (PubMed:20351110). Only traces of products are detected with aspulvinone E or flaviolin as substrates; and no product is formed with L-tryptophan, L-tyrosine, or 4-hydroxyphenylpyruvate (PubMed:20351110). Ptf seems no to be involved in the prenylation reaction in the biosynthesis of aspulvinone H and J and the physiological function of ptf remains unknown (PubMed:20351110). The gene is not located within a recognizable secondary metabolic gene cluster. Belongs to the aromatic prenyltransferase family.