Hop diffusion
Hop diffusion is a non-Brownian diffusion of proteins and lipid molecules within the plasma membrane.
Hop diffusion occurs due to the discontinuity of the cell cytoplasmic membrane.
According to the [fences and pickets model of cell membrane|plasma membrane structure|fences and pickets model], plasma membrane is compartmentalized by actin-based membrane-skeleton "fences", that occur when cytoplasmic domains collide with the actin-based membrane skeleton; and anchored-transmembrane protein "pickets". Due to these obstacles membrane proteins undergo temporary confinement within 30–700- nm compartments with infrequent intercompartmental hops.
Hops between adjacent compartments occur due to:
- thermal fluctuations of the membrane and following creation of spaces between cytoplasmic membrane layer and cytoskeleton, large enough to allow the passage of integral membrane proteins
- temporal actin filament breakage
- membrane molecules have sufficient kinetic energy to cross the barrier