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Figure 3
Comparing calcium binding of PAD6 and PAD4. (a) Sequence alignment of human PAD6 and other PADs focused on regions containing PAD4 residues involved in Ca1, Ca2, Ca3–5. The arrows point to residues involved in Ca2+ coordination in PAD4. The red arrows, with associated letters, highlight residues not conserved and unable to coordinate Ca2+ in PAD6. (b) Close-up views of PAD6 regions equivalent to Ca2+-binding sites in PAD4. Below, PAD4 Ca2+-binding sites are shown for reference (PDB entry 2dew). The yellow spheres represent the Ca2+ ions in PAD4. Residues that differ between the two proteins for which the side chain cannot coordinate Ca2+ in PAD6 are highlighted in red (equivalent positions between PAD6 and PAD4 are indicated with letters in brackets). (c) Thermal stability profiles of PAD4 and PAD6 in the presence of 0 or 10 mM CaCl2. The table provides the average protein melting temperatures (determined as the inflection point of the thermal transition) and the standard deviation from triplicate measurements.

IUCrJ
Volume 11| Part 3| May 2024| Pages 395-404
ISSN: 2052-2525
https://doi.org/10.1107/S2052252524002549