3D Mapping of Individual Ion Channels on Living Cells

Binding of fluorescence labeled hongotoxin to the voltagegatedpotassium channel KV 1.3 was utilized to visualize the 3-dimensional positions of the channels within the plasma membrane of human T lymphocytes in vivo. The position of individual proteins was determined with an accuracy of 40nm laterally and 120nm axially. Successive imaging of the same cell allowed to determine the 3D trajectory of individual ion channels, showing a very low mobility close to immobilization. The presented methodology allows for ultrafast imaging and quantification of the number of individual KV 1.3 molecules expressed on single cells, yielding the captivating perspective of in vivo single molecule pharmacology.