FIG. 3.

Cid1 complexes purified from S. pombe show strong PUP but weak PAP activity. (A) cid1Δ cells (h⁻ cid1::ura4⁺ leu1-32 ura4-D18), transformed with pREPNTAP Cid1 or pREPNTAP DADA, were grown to saturation in minimal medium lacking thiamine. TAP-Cid1 complexes were purified with IgG-Sepharose. Polymerase assays were performed as described in the legend to Fig. 1. (B) Cid1 complexes were incubated with a 5′-labeled (A)₁₅ primer, either 1 mM Mg²⁺ or 1 mM Mn²⁺ (shown with Mg²⁺ and Mn²⁺), and either ATP, CTP, GTP, or UTP (A, C, G, or U, respectively). (C) cdc27 cells (h⁻ cdc27-P11 leu1-32) transformed with pREPNTAP Cid1 were grown to mid-exponential log phase in minimal medium lacking thiamine at 30°C. These cells were then shifted to 36°C for 4 h before being harvested. Purified Cid1 complexes were incubated with a 5′-labeled (A)₁₅ primer and either ATP, CTP, GTP, or UTP (A, C, G, or U, respectively).