title: Calcium cooperativity of exocytosis as a measure of Ca²+ channel domain overlap.
abstract: The number of Ca(2+) channels contributing to the exocytosis of a single neurotransmitter vesicle in a presynaptic terminal has been a question of significant interest and debate, and is important for a full understanding of localized Ca(2+) signaling in general, and synaptic physiology in particular. This is usually estimated by measuring the sensitivity of the neurotransmitter release rate to changes in the synaptic Ca(2+) current, which is varied using appropriate voltage-clamp protocols or via pharmacological Ca(2+) channel block under the condition of constant single-channel Ca(2+) current. The slope of the resulting log-log plot of transmitter release rate versus presynaptic Ca(2+) current is termed Ca(2+)current cooperativity of exocytosis, and provides indirect information about the underlying presynaptic morphology. In this review, we discuss the relationship between the Ca(2+) current cooperativity and the average number of Ca(2+) channels participating in the exocytosis of a single vesicle, termed the Ca(2+)channel cooperativity. We relate these quantities to the morphology of the presynaptic active zone. We also review experimental studies of Ca(2+) current cooperativity and its modulation during development in different classes of synapses.
authors.affiliation: Department of Mathematical Sciences, NJIT, University Heights, Newark, NJ 07102-1982, USA.
authors.forename: Victor
authors.initials: V
authors.lastname: Matveev
authors.forename: Richard
authors.initials: R
authors.lastname: Bertram
authors.forename: Arthur
authors.initials: A
authors.lastname: Sherman
mesh_terms: D000818:Animals; D015220:Calcium Channels / Q000737:chemistry / Q000502:physiology*; D020013:Calcium Signaling / Q000502:physiology*; D002490:Central Nervous System / Q000166:cytology* / Q000502:physiology*; D005089:Exocytosis / Q000502:physiology*; D006801:Humans; D017434:Protein Structure, Tertiary / Q000502:physiology; D013569:Synapses / Q000502:physiology*
chemical_list: D015220:Calcium Channels