2L5X:
reference: The IL1alpha-S100A13 heterotetrameric complex structure: a component in the non-classical pathway for interleukin 1alpha secretion., Mohan SK, Yu C, J Biol Chem. 2011 Apr 22;286(16):14608-17. Epub 2011 Jan 26. PMID: 21270123

This OCA Structure page
uses Jmol, developed by the Jmol Development Team (documentation).