Extended Data Fig. 10: Proposed configuration of PCNA interaction with L1 ORF2p.

(a) Top panel: the predicted PCNA interaction domain (PIP box)¹⁸ within the NTE domain is highlighted. Bottom panel: putative orientation of the PCNA trimer and L1 ORF2p based on existing structures of PCNA with PIP-box containing protein complexes (PDB 7NV0). Based on the superposition of the PIP box, PCNA would be expected to interact near the face of L1 ORF2p for entry of nucleic acids (DNA and RNA), not near the exit channel of the product duplex. (b) Denaturing gel analysis of TPRT reactions with L1 ORF2p in the presence of equimolar PCNA with AJh 25 A (141 nt) as the template RNA. The experiment was replicated three times. Full-length cDNA product was quantified as the relative TPRT product, normalized by the full-length cDNA product without PCNA, and its mean and standard deviation of error across three replicates are displayed below.