Chemistry of ion coordination and hydration revealed by a K+ channel-Fab complex at 2.0 Å resolution 

Yufeng Zhou, João H. Morais-Cabral, Amelia Kaufman, Roderick MacKinnon 

Nature, 414, 43 - 48, ( 2001)

Protein Data Bank accession codes 1K4C and 1K4D

CHESS, F1/A1, ADSC Quantum-4, Quantum-210 CCD