4DBL:
reference: Asymmetric states of vitamin B12 transporter BtuCD are not discriminated by its cognate substrate binding protein BtuF., Korkhov VM, Mireku SA, Hvorup RN, Locher KP, FEBS Lett. 2012 Apr 5;586(7):972-6. Epub 2012 Mar 8. PMID: 22569249

This OCA Structure page
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