Synaptotagmins in membrane traffic: which vesicles do the tagmins tag?

Area of Science:

• Molecular Biology
• Cell Biology
• Neuroscience

Background:

• Synaptotagmin I is a key protein in Ca(2+)-induced exocytosis, found in synaptic vesicles and secretory granules.
• Synaptotagmins belong to the C2 domain-protein family, with eleven genes identified in rodents.
• The functions of most synaptotagmin isoforms, beyond synaptotagmin I and II, remain largely unknown.

Purpose of the Study:

• To provide a comprehensive overview of the current knowledge regarding the synaptotagmin protein family.
• To review available data on the localization and potential functions of various synaptotagmin isoforms.
• To highlight interactions of synaptotagmins with the exocytosis-endocytosis machinery.

Main Methods:

• Literature review focusing on published data concerning synaptotagmin isoforms.
• Analysis of in vitro interaction studies involving synaptotagmins.
• Detailed examination of published data on synaptotagmin subcellular localization.

Main Results:

• Synaptotagmin I's crucial role in Ca(2+)-induced exocytosis is established.
• Numerous in vitro interactions of synaptotagmin I with exocytosis components have been documented.
• Emerging data on other synaptotagmins' interactions and localization are presented, suggesting isoform-specific functions.

Conclusions:

• The diverse synaptotagmin family likely exhibits specialized roles in cellular processes.
• Subcellular distribution is a critical factor influencing the in vivo interactions of different synaptotagmin isoforms.
• Further research into synaptotagmin localization is essential for understanding their specific functions.