Reaction of complex Tp1:PrIV with dCTP, rCTP or β-l-dTTP catalyzed by AMV reverse transcriptase (lanes 2–10) and DNA polymerase I (lanes 11–17). Lane 1, complex Tp1:PrIII (control); lane 2, complex Tp1:PrIV (control); lanes 3 and 11, complex Tp1:PrIV + enzyme (controls); lane 4, as 3 + 5 µM dGTP; lanes 5 and 6 and 12 and 13, as 3 and 11 + dCTP (50 µM for 5 and 12 and 500 µM for 6 and 13, respectively); lanes 7 and 8 and 14 and 15, as 3 and 11 + rCTP (50 µM for 7 and 14 and 500 µM for 8 and 15, respectively); lanes 9 and 10 and 16 and 17, as 3 and 11 + β-l-dTTP (50 µM for 9 and 16 and 500 µM for 10 and 17, respectively).