Neurotransmitter release from presynaptic boutons occurs at specialized regions of the plasma membrane, the active zones. These structures are characterized by a dense protein cytomatrix, the components of which are involved in the regulation of multiple presynaptic functions (Gundelfinger & Fejtova, 2012). Our interest focuses on mechanisms underlying the formation, function and plasticity of these presynaptic specializations using molecular and cellular approaches and mouse genetics.