Macroscopic ion channel currents (I) are a product of the channel open probability (Po), the single channel current (i) and the number of channels present on the cell surface (N) at any given time (I=PoiN). Endocytosis has been shown to be one of the key determinants of cell surface channel density and defects of this process have been linked to diseases relating to ion channel dysfunction. Biotinylation allows the selective labelling and isolation of surface exposed proteins which can then be identified by Western blotting.
