Figure 1.

Target search mechanisms inside a cell.

Facilitated diffusion consists of cycles of non-specific binding to the DNA strand after three-dimensional (3D) search. This is followed by lateral diffusive motions along the DNA strand: (1) sliding, characterized by tight interactions with the strand. (2) Hopping consists of short dissociations away from the strand, however the movement is correlated along the strand. (3) Intersegmental transfer allows a protein with multiple binding sites to momentarily bind first to one than the other strand in a hand-over process. Lastly (4) jumping or 3D-diffusion allows the protein to diffuse in an uncorrelated manner to new DNA sites.