Figure 3.
Gene Family Expansion and PCNA
(A) Gene family expansion. Numbers in red correspond to the predicted number of gene expansion events during mammalian evolution. Mean divergence time estimates were used from TimeTree (Hedges et al., 2006) for scaling.
(B) Multiple sequence alignment of PCNA residues 28–107, showing bowhead whale-specific duplication (gene IDs: bmy 16007 and bmy 21945). Lineage-specic amino acids in the duplicated PCNA of bowhead whales are highlighted in red.
(C) Crystal structure of the PCNA (green) and FEN-1 (yellow) complex. Lineage-specific residues on the PCNA structure are colored in red. A zoom in on the structures reveals a putative interaction between two β sheets, one within PCNA and another within FEN-1. This interaction may be altered through a second interaction between the PCNA β sheet and a lineage-specic change from glutamine to histidine within PCNA. Distance measurements between pairs of atoms are marked in black. PDB accession number: 1UL1.