Function
Catalyzes the condensation of 6-hydroxymethyl-7,8-dihydropterin pyrophosphate (DHPP) with 4-(beta-D-ribofuranosyl)-aminobenzene-5'-phosphate (beta-RFA-P) to form 7,8-dihydropterin-6-methyl-4-(beta-D-ribofuranosyl)-aminobenzene-5'-phosphate, a precursor in the biosynthesis of 5,6,7,8-tetrahydromethanopterin (H4MPT). To a lesser extent, is able to condense beta-RFA-P with another arylamine, 1-(4-aminophenyl)-1-deoxy-D-ribitol (APDR), to form 7,8-dihydropterin-6-methyl-1-(4-aminophenyl)-1-deoxy-D-ribitol. Dephosphorylated beta-RFA-P is not a substrate.