4F4J:
reference: Conversion of the enzyme guanylate kinase into a mitotic-spindle orienting protein by a single mutation that inhibits GMP-induced closing., Johnston CA, Whitney DS, Volkman BF, Doe CQ, Prehoda KE, Proc Natl Acad Sci U S A. 2011 Nov 1;108(44):E973-8. Epub 2011 Oct 11. PMID: 21990344

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