Fig. 5. Comparison of HprK/P with cytidylate and adenylate kinases. The conserved α/β structural motif is highlighted in yellow ribbon in the HprK/P subunit and the two proteins with the highest DALI scores, E.coli cytidine monophosphate kinase (CMPK, PDB code 1cke) and B.stearothermophilus adenylate kinase (ADK, PDB code 1zin). The conserved nucleotide-binding motif includes a five-stranded parallel β-sheet and two α-helices (with the P-loop highlighted in red). However, in HprK/P, βB (in blue) is antiparallel to the other four strands whilst all strands in CMPK and ADK are parallel and the topology differs.