Structure-function analysis of the ion channel selectivity filter in human annexin V

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Science  15 Oct 1993:
Vol. 262, Issue 5132, pp. 427-430
DOI: 10.1126/science.7692599


Electrophysiology and structural studies were performed on an annexin V variant containing a mutation of glutamic acid-95 to serine in the center of the pore region. The mutation resulted in a lower single channel conductance for calcium and a strongly increased conductance for sodium and potassium, indicating that glutamic acid-95 is a crucial constituent of the ion selectivity filter. There were only minor differences in the crystal structures of mutant and wild-type annexin V around the mutation site; however, the mutant showed structural differences elsewhere, including the presence of a calcium binding site in domain III unrelated to the mutation. Analysis of the membrane-bound form of annexin V by electron microscopy revealed no differences between the wild type and mutant.