The Making of Synaptic Ribbons: How They Are Built and What They Do

synapses is the synaptic ribbon. Synaptic ribbons are large presynaptic structures associated with the active zone. They immobilize large amounts of release-ready synaptic vesicles close to the presynaptic vesicle release sites where voltage-dependent calcium channels are con-centrated. Synaptic ribbons are considered to tune the synaptic vesicle cycle for precision, speed, and endurance in a dynamic manner. Multiple roles have been proposed for the ribbons (Parsons and Sterling 2003; Sterling and Matthews 2005; LoGiudice and Matthews 2009), but the precise function of synaptic ribbons and their mode of action are still unclear. The function of synaptic rib-bons depends on its composition. Progress has been made concerning the molecular identification of ribbon components and the understanding of the construction of synaptic ribbons. Recent physiological analyses dem-onstrated the importance of synaptic ribbons also for fast, synchronous release and emphasized the need of a tight and efficient coupling between presynaptic Ca2+ signal-ing and exocytosis in ribbon synapses. This review sum-marizes recent advances on the identification of synaptic ribbon proteins and emerging perspectives on the struc-ture and function of synaptic ribbons