Probable homophilic and heterophilic cell adhesion molecule involved in long term potentiation at hippocampal excitatory synapses through activation of p38MAPK. May also regulate neurite outgrowth by activating the FGFR1 signaling pathway. May play a role in synaptic plasticity (By similarity). (updated: April 1, 2015)
The data and differentiation stages presented below come from the proteomic study and analysis performed by our partners of the GReX consortium, more details are available in their published work.
No sequence conservation computed yet.
This protein is annotated as membranous in Gene Ontology, is annotated as membranous in UniProt, is predicted to be membranous by TOPCONS.
Total structural coverage: 48%
No model available.
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The reference OMIM entry for this protein is 612820
Neuroplastin; nptn
Stromal cell-derived factor receptor 1; sdfr1 glycoprotein, 55-kd, included; gp55, included
Neuroplastin 55, included; np55, included
Glycoprotein, 65-kd, included; gp65, included
Neuroplastin 65, included; np65, included
DESCRIPTION
Neuroplastin is a cell adhesion molecule of the immunoglobulin (Ig) superfamily and plays a role in synaptic plasticity processes (Bernstein et al., 2007).
CLONING
By screening a rat brain cDNA expression library using monoclonal antibody SMgp65, followed by additional cDNA library screening, Langnaese et al. (1997) cloned rat Nptn. They identified 2 splice variants: a deduced 281-amino acid protein corresponding to the 55-kD glycoprotein (Gp55) species and a deduced 397-amino acid protein containing a 116-amino acid insertion that corresponds to the 65-kD glycoprotein (Gp65) species. Both deduced proteins contain a predicted 28-amino acid signal peptide, and the Gp55 species contains 4 C-terminal residues (DDEP) lacking in the Gp65 species. The deduced mature Gp55 and Gp65 proteins contain 253 and 365 amino acid residues with calculated molecular masses of 28.8 and 41.4 kD, respectively. Both species contain a single putative membrane spanning domain, and Gp55 has 2 extracellular Ig domains whereas Gp65 has 3 extracellular Ig domains. Gp55 shares similarity with basigin (
109480) Ig domain proteins. Immunocytochemical studies localized Gp55 and Gp65 to the cell membrane in HEK293 cells. Northern blot analysis of rat tissues detected a 2.5-kb Gp65 transcript and 2.2-kb Gp55 transcript in several brain regions; however, the 2.5-kb transcript showed a brain-specific distribution, whereas the 2.2-kb transcript was detected in other tissues including kidney, spleen, thymus, skeletal muscle, heart, and liver. In situ hybridization detected both transcripts in rat brain, with a more restricted distribution noted for the 2.5-kb transcript. Langnaese et al. (1997) stated that Gp65 is most enriched in the postsynaptic density (PSD) fraction. Expression analysis in postnatal rat brain showed that Gp55 was detected at all stages, whereas Gp65 was low initially, increased steadily to postnatal day 20 to 25, and then declined to an intermediate level. Bernstein et al. (2007) noted that human NPTN contains 2 isoforms termed NP65 and NP55, similar to the Nptn isoforms detected in rat. Immunohistochemical studies localized the 2 NPTN isoforms in brain tissue. Bernstein et al. (2007) noted that unlike the rat ortholog, the human NP65 isoform was not detected in the hippocampus. Human brain NP65 displayed a predominant localization to the cerebellum, in contrast to earlier observation of rat Np55 as the predominant isoform in mouse and rat cerebellum.
GENE FUNCTION
Using immunoaffinity chromatography and mass spectrometry, followed by coprecipitation and FRET analysis, Sarto-Jackson et al. (2012) found that rat Np, predominantly the brain-specific Np65 isoform, interacted with subunits of the rat GABA(A) receptor (see GABRA1;
137160). In cultured embryonic rat hippocampal neurons and in adult hippocampal sections, a portion of GABA(A) receptors colocalized with Np in clusters at both synaptic and extrasynaptic sites. Knockdown of Np in primary hippocampal neurons via short hairpin RNA led to diffuse staining for the alpha-2 GABA(A) receptor subunit (GABRA2;
137140) at GABAergic synapses. Sarto-Jackson et al. (2012) proposed that NP may contribute to GABA(A) receptor anchoring at specific sites and affect synaptic strength.
MAPPING
Hartz (2013) mapped the NPTN gene to chromosome 15q24.1 based on an alignment of the NPTN sequence (GenBank GENBANK AF
035287) with the genomic sequence (GRCh37). ...
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Subscribe to this protein entry history
Feb. 2, 2018: Protein entry updated
Automatic update: Uniprot description updated
Dec. 19, 2017: Protein entry updated
Automatic update: Uniprot description updated
Nov. 23, 2017: Protein entry updated
Automatic update: Uniprot description updated
March 25, 2017: Additional information
No protein expression data in P. Mayeux work for NPTN
March 16, 2016: Protein entry updated
Automatic update: OMIM entry 612820 was added.