| Annotated protein: | Synaptotagmin-1 (Synaptotagmin I) (SytI) (p65). Gene symbol: SYT1. Taxonomy: Mus musculus (Mouse). Uniprot ID: P46096 |
| antibody wiki: | |
| SynGO gene info: | SynGO data @ SYT1 |
| Ontology domain: | Biological Process |
| SynGO term: | calcium-dependent activation of synaptic vesicle fusion (GO:0099502) |
| Synapse type(s): | hippocampus, glutamatergic |
| Annotated paper: | Geppert M, et al. "Synaptotagmin I: a major Ca2+ sensor for transmitter release at a central synapse" Cell. 1994 Nov 18;79(4):717-27 PMID:7954835 |
| Figure(s): | Fig. 3, 7, 8, Table 2 |
| Annotation description: | In this paper, Geppert et al generate a KO of syt-1 gene and observe severe impact of the genetic manipulation on the survival rate of the KO animals (die within 48 h after birth). Morphological, biochemical and electrophysiological tests (Fig. 1, 2, 4, 5, 6) don't show any differences in the expression of synaptic proteins, changes in synapse structures or any impairments of basic exocytotic machinery (similar absolute rate of mEPSC, hypertonic sucrose application response and alpha latrotoxin evoked transmission). However, the authors demonstrate massively attenuated EPSCs upon evoked synaptic responses (in pairs of pyramidal neurons by whole-cell patch clamping). Furthermore, analysis of the fast and slow component of release (synchronous and asynchronous, respectively) reveals that the fast component is almost absent in mutant mice (Fig. 7, 8, Table 2). Based on this, Geppert et al conclude that the lack of syt-1 abolishes normal synchronous release. By assessing the Ca2+- dependence of the size of residual evoked response by a described method (Dodge-Rahamimoff), the authors confirm intact Ca-dependence of release machinery in mut as well as in WT animals and that the decreased synaptic activity is due to selective decrease in Ca-triggered release (Fig. 9). |
| Evidence tracking, Biological System: | Cultured neurons |
| Evidence tracking, Protein Targeting: | Genetic transformation (eg; knockout, knockin, mutations) Antibody (detection) |
| Evidence tracking, Experiment Assay: | Electron Microscopy Whole-cell patch clamp Electrophysiology (generic) Western blot |
| Annotator(s): | Momchil Ninov (ORCID:0000-0002-0808-7003) Mahdokht Kohansalnodehi (ORCID:0000-0002-3898-5197) Reinhard Jahn (ORCID:0000-0003-1542-3498) |
| Lab: | Department of Neurobiology, Max Planck Institute for Biophysical Chemistry, 37077 Göttingen, Germany |
| Additional literature: | In this paper, Brose et al. purify native synaptotagmin-1 via affinity chromatography and measure Ca2+ binding in the absence and presence of phospholipids using equilibrium dialysis. Ca2+ binding occurs only in the presence of membranes containing PS and PC (Fig.1). Furthermore, the interaction between syt-1 and liposomes containing acidic phospholipids is investigated by FRET. The data show that Ca2+ triggers association of the protein with liposomes interaction, with no other metal ions being able to substitute (Fig. 2 A and B). Additionally, by applying FRET, the authors show that syt-1 is able to bind to liposomes in the presence of Ca2+ even if the protein itself is incorporated in a liposome (Fig. 2C). @ PMID:1589771 In this report, Perin et al report on the domain architecture of synaptotagmin 1 (termed p65) containing anN-terminal TMR and C2-domains with similarity to PKC's regulatory domains (Fig. 2). Additionally, the authors demonstrate that the cytoplasmic domain of recombinant syt-1 (p65) binds specifically acidic phospholipids in a mode similar to PKC (Fig. 3). Based on their results, the authors suggest a role of syt-1 in synaptic vesicle exocytosis involving its binding affinity toward acidic membrane lipids. @ PMID:2333096 The authors report on deletion of synaptotagmin 1 gene, snt-1, in C.elegans which diminishes synaptic exocytosis causing abnormalities in behaviour, locomotion, feeding and defecation. Furthermore, due to attenuated exocytosis, acetylcholine accumulates at the nerve terminals. @ PMID:8391930 Prior to the report on murine syt-1 KO, Littleton et al generated Drosophila flies with syt gene mutation and demonstrate, apart from failure in hatching and uncoordinated muscle contraction, extreme reduction of evoked excitatory junctional potentials (EJPs) and their amplitude. Thus, the authors provide direct evidence for the key role of syt in Ca2+-triggering of neurotransmitter release. @ PMID:8104705 Fig. 3, Table 1, Fig. 5A, Fig. 6-8: In this study, the authors focus on a point mutation that reduces the Ca2+ affinity of synaptotagmin 1 twofold without affecting its 3D structure. Using genetic replacement in mice, When introduced by homologous recombination into the endogenous synaptotagmin I gene in mice, this point mutation decreases the Ca2+ sensitivity of neurotransmitter release twofold, but does not alter spontaneous release or the size of the readily releasable pool of neurotransmitters. In detail, the authors identify two point mutations (substitution of positively charged residues) R233Q and K236Q with no effect on 3D protein structure but having diverse effects on the intrinsic Ca2+ affinity of syt-1 (Fig 2: 1H-15N HSQC NMR). However, overall Ca2+ affinity of the protein is observed in the presence of phospholipid membranes and is a function of complex formation between C2 domains, Ca2+ and phospholipids. Thus, by using a Ca2+-dependent phospholipid binding assay, Fernández-Chacón R., et al. demonstrate that R233Q mutation decreases by twofold the overall Ca2+ affinity of the protein by using recombinant cytoplasmic domains of syt-1 (Fig. 3 and Table 1). In order to confirm the findings, the authors isolate cytoplasmic domains of syt-1 from WT and R233Q animals and repeat the Ca2+-dependent phospholipid binding assay. Despite of the similar extent of binding of R233Q mutant and WT C2A/C2B domain, the overall Ca2+ affinity for the mutant is twofold lower as for WT (Fig. 5a). By electrophysiological experiments, the authors demonstrate smaller EPSC amplitudes for R233Q mice (Fig. 6), however, they observe large facilitation after high frequency stimulation. The latter one is shown to be due to reduced release probability (Fig. 7) caused by a decrease in Ca2+ triggering response of SV exocytosis (Fig. 8). @ PMID:11242035 |
| SynGO annotation ID: | 1610 |
| Dataset release (version): | 20231201 |
| View annotation as GO-CAM model: |  |