3HKL:
reference: Crystal Structure of the Frizzled-Like Cysteine-Rich Domain of the Receptor Tyrosine Kinase MuSK., Stiegler AL, Burden SJ, Hubbard SR, J Mol Biol. 2009 Aug 4. PMID: 19664639

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