DLG1

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Discs, large homolog 1 (Drosophila)
Protein DLG1 PDB 1iu0.png
PDB rendering based on 1iu0.
Available structures
PDB Ortholog search: PDBe, RCSB
Identifiers
Symbols DLG1 ; DLGH1; SAP-97; SAP97; dJ1061C18.1.1; hdlg
External IDs OMIM601014 MGI107231 HomoloGene20869 GeneCards: DLG1 Gene
RNA expression pattern
PBB GE DLG1 202515 at tn.png
PBB GE DLG1 202514 at tn.png
PBB GE DLG1 202516 s at tn.png
More reference expression data
Orthologs
Species Human Mouse
Entrez 1739 13383
Ensembl ENSG00000075711 ENSMUSG00000022770
UniProt Q12959 Q811D0
RefSeq (mRNA) NM_001098424 NM_001252433
RefSeq (protein) NP_001091894 NP_001239362
Location (UCSC) Chr 3:
196.77 – 197.03 Mb
Chr 16:
31.66 – 31.87 Mb
PubMed search [1] [2]

Disks large homolog 1 (DLG1), also known as synapse-associated protein 97 or SAP97, is a protein that in humans is encoded by the SAP97 gene.

SAP97 is a mammalian MAGUK-family member protein that is similar to the Drosophila protein Dlg1 (the protein is alternatively referred to as hDlg1, and the human gene is DLG1). SAP97 is expressed throughout the body in epithelial cells. In the brain it is involved in the trafficking of ionotropic receptors from the endoplasmic Reticulum to the plasma membrane, and may be involved in the trafficking AMPAR during synaptic plasticity.

Function[edit]

SAP97 is expressed throughout the body in epithelial cells, including the kidney and brain.[1] There is some evidence that SAP97 regulates cell-to-cell adhesion during cell death, and may interact with HPV. In the brain, SAP97's function is involved in the trafficking of transmembrane receptors from the ER to the plasma membrane.[2]

SAP97's function has been investigated by reducing its expression by knockout or increasing its expression heterologously. Mice in which the SAP97 gene has been knocked out die perinatally, have a cleft palate, and deficiencies in renal function.[3][4] Overexpression of SAP97 in mammalian neurons leads to increased synaptic strength.[5]

Clinical significance[edit]

Mutations in DLG1 are associated to Crohn's Disease .[6]

Structure[edit]

SAP97's protein structure consists of an alternatively-spliced n-terminal domain, three PDZ domains, an SH3 domain, hook domain, I3 domain, and finally an inactive guanylate kinase (GK) domain. Each of these domains has specific interacting partners that help define SAP97's unique function.

The n-terminal of SAP97 can be alternatively spliced to contain a double-cysteine/palmitoylation site (α-isoform), or an L27 domain (β-isoform. The L27 domain is involved in SAP97 oligomerization with other SAP97 molecules, CASK, and other L27-domain-containing proteins.[7] There is also a myosin VI binding site near n-terminal which may be involved in the internalization of AMPAR.[8][9]

Each of SAP97's PDZ domains have different binding partners, including the AMPAR subunit GluR1[10][11] for the first PDZ domain, and neuroligin for the last. SAP97's I3 domain is unique to SAP97 among the MAGUK family, and is known to regulate the post-synaptic localization of SAP97[5] and to bind the protein 4.1N. The GK domain allows SAP97 to bind to GKAP/SAPAP-family proteins.

References[edit]

  1. ^ Müller BM, Kistner U, Veh RW et al. (March 1995). "Molecular characterization and spatial distribution of SAP97, a novel presynaptic protein homologous to SAP90 and the Drosophila discs-large tumor suppressor protein". J. Neurosci. 15 (3 Pt 2): 2354–66. PMID 7891172. 
  2. ^ Sans N, Racca C, Petralia RS, Wang YX, McCallum J, Wenthold RJ (October 2001). "Synapse-associated protein 97 selectively associates with a subset of AMPA receptors early in their biosynthetic pathway". J. Neurosci. 21 (19): 7506–16. PMID 11567040. 
  3. ^ Caruana G, Bernstein A (March 2001). "Craniofacial dysmorphogenesis including cleft palate in mice with an insertional mutation in the discs large gene". Mol. Cell. Biol. 21 (5): 1475–1483. doi:10.1128/MCB.21.5.1475-1483.2001. PMC 86693. PMID 11238884. 
  4. ^ Mahoney ZX, Sammut B, Xavier RJ et al. (December 2006). "Discs-large homolog 1 regulates smooth muscle orientation in the mouse ureter". Proc. Natl. Acad. Sci. U.S.A. 103 (52): 19872–19877. doi:10.1073/pnas.0609326103. PMC 1750896. PMID 17172448. 
  5. ^ a b Rumbaugh G, Sia GM, Garner CC, Huganir RL (June 2003). "Synapse-associated protein-97 isoform-specific regulation of surface AMPA receptors and synaptic function in cultured neurons". J. Neurosci. 23 (11): 4567–76. PMID 12805297. 
  6. ^ Xu, S; Zhou, F; Tao, J; Song, L; Ng, S. C.; Wang, X; Chen, L; Yi, F; Ran, Z; Zhou, R; Xia, B (2014). "Exome Sequencing Identifies DLG1 as a Novel Gene for Potential Susceptibility to Crohn's Disease in a Chinese Family Study". PLoS ONE 9 (6): e99807. doi:10.1371/journal.pone.0099807. PMID 24937328.  edit
  7. ^ Lee S, Fan S, Makarova O et al. (March 2002). "A novel and conserved protein-protein interaction domain of mammalian Lin-2/CASK binds and recruits SAP97 to the lateral surface of epithelia". Mol. Cell. Biol. 22 (6): 1778–1791. doi:10.1128/MCB.22.6.1778-1791.2002. PMC 135599. PMID 11865057. 
  8. ^ Wu H, Nash JE, Zamorano P, Garner CC (August 2002). "Interaction of SAP97 with minus-end-directed actin motor myosin VI. Implications for AMPA receptor trafficking". J. Biol. Chem. 277 (34): 30928–30934. doi:10.1074/jbc.M203735200. PMID 12050163. 
  9. ^ Osterweil E, Wells DG, Mooseker MS (January 2005). "A role for myosin VI in postsynaptic structure and glutamate receptor endocytosis". J. Cell Biol. 168 (2): 329–338. doi:10.1083/jcb.200410091. PMC 2171578. PMID 15657400. 
  10. ^ Leonard AS, Davare MA, Horne MC, Garner CC, Hell JW (July 1998). "SAP97 is associated with the alpha-amino-3-hydroxy-5-methylisoxazole-4-propionic acid receptor GluR1 subunit". J. Biol. Chem. 273 (31): 19518–19524. doi:10.1074/jbc.273.31.19518. PMID 9677374. 
  11. ^ Cai C, Coleman SK, Niemi K, Keinänen K (August 2002). "Selective binding of synapse-associated protein 97 to GluR-A alpha-amino-5-hydroxy-3-methyl-4-isoxazole propionate receptor subunit is determined by a novel sequence motif". J. Biol. Chem. 277 (35): 31484–31490. doi:10.1074/jbc.M204354200. PMID 12070168. 

Further reading[edit]

External links[edit]