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Symbol SYNJ1 contributors: mct/npt - updated : 04-01-2015
HGNC name synaptojanin 1
HGNC id 11503
Corresponding disease
EIEE53 epileptic encephalopathy, early infantile, 53
PARK20 Parkinson disease 20, early-onset
Location 21q22.11      Physical location : 34.001.068 - 34.100.351
Synonym name
  • inositol 5'-phosphatase (synaptojanin 1)
  • synaptojanin-1, polyphosphoinositide phosphatase
  • Synonym symbol(s) INPP5G, KIAA0910, SJ1
    TYPE functioning gene
    STRUCTURE 103.08 kb     32 Exon(s)
    10 Kb 5' upstream gene genomic sequence study
    MAPPING cloned Y linked N status confirmed
    Physical map
    HUNK 21q22.1 hormonally upregulated Neu-associated kinase C21orf45 21q22.11 chromosome 21 open reading frame 45 C21orf61 21q22.1 chromosome 21 open reading frame 61 C21orf119 21 chromosome 21 open reading frame 119 C21orf63 21q22.11 chromosome 21 open reading frame 63 C21orf77 21q22.11 chromosome 21 open reading frame 7 TCP10L 21q22.11 t-complex 10 (mouse)-like C21orf59 21q22.1 chromosome 21 open reading frame 59 LOC391279 21 similar to putative taste receptor HTR2 SYNJ1 21q22.1-q22.2 synaptojanin 1 C21orf66 21q22.11 chromosome 21 open reading frame 66 C21orf62 21q22.1 chromosome 21 open reading frame 62 OLIG2 21q22.11 oligodendrocyte lineage transcription factor 2 C21orf54 21q22.11 chromosome 21 open reading frame 54 IFNAR2 21q22.1 interferon (alpha, beta and omega) receptor 2 IL10RB 21q22.1-q22.2 interleukin 10 receptor, beta IFNAR1 21q22.1 interferon (alpha, beta and omega) receptor 1 IFNGR2 21q22.1 interferon gamma receptor 2 (interferon gamma transducer 1) C21orf4 21q22.1-q22.2 chromosome 21 open reading frame 4 RPS5L 21q22.11 ribosomal protein S5-like C21orf55 21q22.11 chromosome 21 open reading frame 55 GART 21q22.1 phosphoribosylglycinamide formyltransferase, phosphoribosylglycinamide synthetase, phosphoribosylaminoimidazole synthetase
    TRANSCRIPTS type messenger
    identificationnb exonstypebpproduct
    ProteinkDaAAspecific expressionYearPubmed
    32 splicing 7075 173.1 1570 nonneuronal ubiquitously expressed 2006 17158794
    present at all stages of clathrin-coated pit formation
    32 splicing 7099 144.86 1311 predominant isoform expressed in the brain 2006 17158794
    rapidly recruited as a "burst," together with endophilin, at a late stage of clathrin-coated pits formation
    28 - 6942 - 1526 - 2006 17158794
    32 - 7059 1432.25 1295 - 2006 17158794
       expressed in (based on citations)
    SystemOrgan level 1Organ level 2Organ level 3Organ level 4LevelPubmedSpeciesStageRna symbol
    Endocrineneuroendocrinepituitary  predominantly
    Nervousbrain   highly
     nervecranial nerve  moderately
    Reproductivefemale systemplacenta  highly
     male systemprostate   
    Visualeyeretina    Danio rerio
    SystemTissueTissue level 1Tissue level 2LevelPubmedSpeciesStageRna symbol
    Blood / hematopoieticbone marrow   
    SystemCellPubmedSpeciesStageRna symbol
    Visualcone photoreceptor Danio rerio
    cell lineage
    cell lines
    at STAGE
    physiological period embryo, pregnancy
    Text developing brain, placenta
  • N-terminal Sac1 phosphatase domain
  • a central 5- phosphatase domain
  • a C-terminal proline-rich domain with catalytic activity required for normal synaptic vesicle internalization and reavailability (Mani 2007)
  • a SAC1 like phosphatase domain
  • one RNA recognition motif (RRM)
  • a C terminal proline-rich region
    interspecies homolog to rattus Synj1 (90.4 pc)
    homolog to murine Synj1 (90.4 pc)
  • inositol-1, 4, 5-triphosphate 5-phosphatase family
  • CATEGORY enzyme , transport
    SUBCELLULAR LOCALIZATION     intracellular
  • secretory vesicles
  • mostly expressed in the synaptic terminals of neurons (Herrera 2009)
  • basic FUNCTION
  • polyphosphoinositide phosphatase, key factor controlling the level of PtdIns(4,5)P2 required for proper neurotransmission
  • playing an essential role in synaptic vesicle recycling
  • acting as a negative regulator of clathrin coats
  • playing a role in neurological manifestations in Down syndrome
  • also required for normal vesicle endocytosis (Mani 2007)
  • playing a critical role for retrieval of membrane in order to maintain the quantity, timing of fusion, and spontaneous release properties of synaptic vesicles at hair-cell ribbon synapses
  • major regulators of inositol metabolism and signaling in the brain and involved in astrogliogenesis
  • may have a possible role for astrocytes or astrogliogenesis in Doiwn syndrome
  • polyphosphoinositide phosphatase involved in clathrin-mediated endocytosis in conventional synapses
  • acts with membrane curvature generators/sensors, such as the BAR protein endophilin, to preferentially remove PI(4,5)P2 from curved membranes as opposed to relatively flat ones
  • key regulator of the signalling phospholipid phosphatidylinositol-4,5-biphosphate that regulate clathrin-mediated endocytosis
  • involvement of SYNJ1 in endosomal abnormalities is consistent with the finding that the 145 kDa isoform interacts with endocytic SH3 domain-containing proteins, such as endophilin, amphiphysin and intersectin
    PHYSIOLOGICAL PROCESS endocytosis transport
    text synaptic vesicle endocytosis
    metabolism other
    phosphate metabolism
    a component
    RNA binding
    small molecule nucleotide,
  • binding to EPS15 (a clathrin coat-associated protein) via a C-terminal domain containing three Asn-Pro-Phe (NPF) repeats
  • binding to a variety of SH3 domain-containing proteins including AMPH, SH3GL1, SH3GL2, SH3GL3 and GRB2 via the C-terminal proline-rich region
  • intersection (ITSN)
  • Sh3p4
  • GRB2
  • directly interact with one another to regulate synaptic vesicle endocytosis and recycling
  • EPS15 (a clathrin coat-associated protein)
  • interacting with DYRK1A (involved in regulating the recruitment activity but not the phosphatase activity of SYNJ1)
  • SYNJ1 and PACSIN1 are potential substrates of PAK7
  • cell & other
    inhibited by cyclin-dependent kinase 5 (Cdk5) phosphorylation
    Phosphorylated by PAK7 (phosphorylation promotes the interaction of SYNJ1 with PACSIN1, implicating PAK7 in synaptic vesicle trafficking)
    corresponding disease(s) PARK20 , EIEE53
    Other morbid association(s)
    TypeGene ModificationChromosome rearrangementProtein expressionProtein Function
    constitutional     --over  
    may affect a variety of synaptic processes, particularly in brain regions normally exhibiting the highest levels of expression, such as the hippocampus
    constitutional     --over  
    contribution of SYNJ1 overexpression to the endosomal changes observed in Down syndrome
    Variant & Polymorphism
    Candidate gene for bipolar disorder
    Therapy target
    SYNJ1 reduction ameliorates Alzheimer disease -associated behavioral and synaptic deficits, providing evidence that SYNJ1 and, more generally, phosphoinositide metabolism may be promising therapeutic targets
    mental retardationtrisomy 
    attractive new target for rescuing endocytic dysfunction and lipid metabolism in Down syndrome
    attractive new target for rescuing endocytic dysfunction and lipid metabolism in AD
  • Synj1-/- mice display elevated steady-state levels of PIP2 with an accumulation of clathrin-coated vesicles in nerve terminals, and these animals die shortly after birth
  • presence of enlarged endosomes in the cortex of transgenic mice overexpressing Synj1