| Annotated protein: | Disks large homolog 3 (PSD-95/SAP90-related protein 1) (Synapse-associated protein 102) (SAP-102) (SAP102). Gene symbol: DLG3. Taxonomy: Rattus norvegicus (Rat). Uniprot ID: Q62936 |
| antibody wiki: | |
| SynGO gene info: | SynGO data @ DLG3 |
| Ontology domain: | Biological Process |
| SynGO term: | structural constituent of postsynaptic density (GO:0098919) |
| Synapse type(s): | hippocampus, glutamatergic |
| Annotated paper: | Zheng CY, et al. "SAP102 is a highly mobile MAGUK in spines" J Neurosci. 2010 Mar 31;30(13):4757-66 PMID:20357126 |
| Figure(s): | Figures 2, 3, 4, 5, 6; Supplementary Figues 3, 4, 5, 6 |
| Annotation description: | Fig. 2: "SAP102 has a larger mobile fraction than PSD-95 in spines" FRAP analysis of GFP-SAP102 and GFP-PSD-95 in spines of cultured hippocampal neurons. 58.1±8.0% and 22.4±3.7% of total GFP-SAP97 in spines was present in the slow and rapid mobile fractions, respectively (24.4±4.0% and 11.7±3.6% for GFP-PSD-95 in the respective fractions). "The total mobile fractions of GFP-SAP102 and GFP-PSD-95 were 80.5±10.2 and 36.2±9.3%, respectively." "SH3/GK domains are required for SAP102 enrichment and stabilization in spines (Fig. 3-4)." "SAP102 lacks the N-terminal cysteine palmitoylation sites, which mediate the synaptic clustering of PSD-95 (supplemental Fig. 3A,B)." Spine enrichment of GFP-SAP102ΔSH3GK was significantly decreased compared to GFP-SAP102. SAP102-PDZ mutants that are unable to bind to group 1 PDZ ligands showed similar spine targeting as GFP-SAP102. FRAP analysis showed GFP-SAP102ΔSH3GK recovered significantly faster than GFP-SAP102 (Fig. 4D,E) and did not detect a slow mobile fraction. "the movement of GFP-SAP102ΔSH3GK in spines is likely due to free diffusion, suggesting that SH3/GK domains are necessary for SAP102 stabilization in spines." SAP102-PDZ mutants had similar recovery patterns as GFP-SAP102 (Fig. 4E),"suggesting that single PDZ mutation does not influence the turnover rate of SAP102 in spines." Fig 5: "SAP102 mobility depends on actin dynamics" FRAP of GFP-SAP102 and GFP-PSD-95 in the presence of the actin stabilizer, jasplakinolide (induces actin polymerization, blocks actin turnover in spines, Fig. 5D). Jasplakinolide treatment increased the immobile and decreased the slow mobile fractions of GFP-SAP102 in spines compared to DMSO controls (Fig. 5E,G). Actin stabilization had no significant effect on the mobility of spine GFP-PSD-95. FIg. 6: "SAP102 and PSD-95 are independently regulated in spines." Overexpression of SAP102 or PSD-95 had no effect on endogenous levels of PSD-95 or SAP102, respectively, in spines (supplemental Fig. 4). Acute blockade of glutamate receptor activity (APV, DNQX) significantly decreased the mobile fraction of spine GFP-SAP102 compared to control treated cells. Actin turnover and the mobility of spine GFP-PSD-95 were unaffected spines (Fig. 6, supplemental Fig. 5-6). Treatment with APV alone inhibited the half recovery time of GFP-SAP102 (supplemental Fig.6A). Conclusion: "Our results suggest that SAP102 and PSD-95 play different roles in the trafficking and organization of glutamate receptors at the synapse, and, therefore, have distinct roles in synaptic plasticity." FRAP analysis: The recovery of fluorescence in spines over 20min was divided into three components: the immobile, the slow mobile, and the rapid mobile fractions. The mobile fraction (sum of slow and rapid mobile fractions) was the total fluorescence recovered in 20 min. "The slow mobile components were defined by FRAP curves, which matched one-phase exponential equations from 10 s to minutes." 1/3/2018 Pim - The participation of SAP102; Synapse-associated protein 102 in the postsynaptic scaffolding complex is also proposed by the authors: "Glutamate receptors are clustered at the postsynaptic membrane of excitatory synapses through interactions with a submembranous scaffolding complex known as the post synaptic density (PSD). This complex is made up of a number of interacting proteins with prominent members being the PSD-95 family of membrane associated guanylate kinases (MAGUKs), which include PSD-95, PSD-93, SAP102, and SAP97. The MAGUKs interact directly with NMDA receptors (Kornau et al., 1995; Muller et al., 1996) and indirectly with AMPA receptors through transmembrane AMPA receptor regulatory proteins (TARPs) (Nicoll et al., 2006)" |
| Evidence tracking, Biological System: | Cultured neurons |
| Evidence tracking, Protein Targeting: | Over-expression Antibody (detection) |
| Evidence tracking, Experiment Assay: | Confocal Fluorescence recovery after photobleaching (FRAP) |
| Annotator(s): | Hana Goldschmidt (ORCID:0000-0002-5676-366X) Richard Huganir (ORCID:0000-0001-9783-5183) |
| Lab: | Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA and Kavli Neuroscience Discovery Institute, Johns Hopkins University, Baltimore, MD 21205, USA |
| Additional literature: | Validation of SAP102 and PSD-95 antibodies used for immunogold labeling. @ PMID:10648730 |
| SynGO annotation ID: | 2726 |
| Dataset release (version): | 20231201 |
| View annotation as GO-CAM model: |  |