Intracellular calcium dependence of large dense-core vesicle exocytosis in the absence of synaptotagmin I.
2001 (English)In: Proceedings of the National Academy of Sciences of the United States of America, ISSN 0027-8424, E-ISSN 1091-6490, Vol. 98, no 20, 11680-5 p.Article in journal (Refereed) Published
Synaptotagmin I is a synaptic vesicle-associated protein essential for synchronous neurotransmission. We investigated its impact on the intracellular Ca(2+)-dependence of large dense-core vesicle (LDCV) exocytosis by combining Ca(2+)-uncaging and membrane capacitance measurements in adrenal slices from mouse synaptotagmin I null mutants. Synaptotagmin I-deficient chromaffin cells displayed prolonged exocytic delays and slow, yet Ca(2+)-dependent fusion rates, resulting in strongly reduced LDCV release in response to short depolarizations. Vesicle recruitment, the shape of individual amperometric events, and endocytosis appeared unaffected. These findings demonstrate that synaptotagmin I is required for rapid, highly Ca(2+)-sensitive LDCV exocytosis and indicate that it regulates the equilibrium between a slowly releasable and a readily releasable state of the fusion machinery. Alternatively, synaptotagmin I could function as calcium sensor for the readily releasable pool, leading to the destabilization of the pool in its absence.
Place, publisher, year, edition, pages
2001. Vol. 98, no 20, 11680-5 p.
Medical and Health Sciences
IdentifiersURN: urn:nbn:se:uu:diva-259848DOI: 10.1073/pnas.201398798PubMedID: 11562488OAI: oai:DiVA.org:uu-259848DiVA: diva2:1061356