Synaptotagmin

spinqualitylabelsall models Synaptostagmin-2 C2A and C2B domains complex with Ca+2 ions (green) (PDB code 4npk) Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Function Synaptotagmin (SYT) are calcium-binding proteins which are conserved from nematodes to humans. Fifteen SYTs have been identified in mammals. Synaptotagmin-1 (SYT1) is a synaptic vesicle membrane protein and is a sensor which induces release in neurons upon binding of Ca+2 ions. The C2A domain of SYT binds phospholipids in Ca+2-dependent manner. The C2B domain of SYT promotes binding to other C2B domains and to accessory proteins. Ca+2 binding causes intramolecular association of domains C2A and C2B. The synaptic fusion apparatus includes the affinity between SYT and Syntaxin-1, This affinity increases by ca. 2 orders of magnitude upon binding of Ca+2. Synaptotagmin-2 is a Ca+2 sensor for fast neurotransmitter release in caudal brain regions. Synaptotagmin-3 is a Ca+2 sensor for fast neurotransmitter release in presynapses. Synaptotagmin-4 regulates membrane traffic in neurons. Synaptotagmin-5 is dense-core vesicle-specific controlling Ca+2-regulated secretion. Synaptotagmin-7 is a plasma membrane Ca+2 sensor in synaptic exocytosis. Synaptotagmin-like proteins (SYTL) are required in a generation of a single apical surface per cell. Relevance Synaptotagmin-4 is up-regulated by chronic depolarization and seizures. Synaptotagmin-1 is a promising biomarker to monitor dysfunction and degeneration in Alzheimer disease. Structural highlights SYT-2 structure contains the SMP (synaptotagmin-like-mitochondrial-lipid binding) domain, followed by the C2A Ca+2-binding, C2B, spacer and C2C domains. At the cup-shaped cavity at the of SYT C2A domain there are three tightly clustered Ca+2 binding sites formed by canonical 5 aspartates. 1st Ca+2 binding site. Water molecules are shown as red spheres. 2nd Ca+2 binding site. 3th Ca+2 binding site. All Ca+2 binding sites. 3D structures of synaptotagmin Synaptotagmin 3D structures

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