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Scientists finger neurexin 1 defects in autism

/Users/rachelbash/Documents/St. Olaf/Neuro/Wiki neurexin picture.pdf

neurexin 1
Identifiers
SymbolNRXN1
NCBI gene9378
HGNC8008
OMIM600565
RefSeqNM_001135659.1
UniProtQ9ULB1
Other data
LocusChr. 2 p16.3
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StructuresSwiss-model
DomainsInterPro
neurexin 2
Identifiers
SymbolNRXN2
NCBI gene9379
HGNC8009
OMIM600566
RefSeqNM_015080
UniProtP58401
Other data
LocusChr. 2 q13.1
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StructuresSwiss-model
DomainsInterPro
neurexin 3
Identifiers
SymbolNRXN3
NCBI gene9369
HGNC8010
OMIM600567
RefSeqNM_001105250
UniProtQ9HDB5
Other data
LocusChr. 14 q31
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StructuresSwiss-model
DomainsInterPro

Neurexins not only bind to neuroligin. Additional binding partners of neurexin are dystroglycan and neuroexophilins. [1] Dytroglycan is Ca2+ dependant and binds preferentially to α-neurexins on LNS domains that lack splice inserts. In mice, a deletion of dystroglycan causes long-term potentiation impairment and developmental abnormalities similar to muscular dystrophy; however baseline synaptic transmission is normal. Neuroexophilins are Ca2+ independent and bind exclusively to α-neurexins on the second LNS domain. The increased startle responses and impaired motor coordination of neuroexophilin knockout mice indicates that neuroexophilins have a functional role in certain circuits. [2] The significance of the relationship between neurexin and dystroglycan or neuroexophilins is still unclear.

Expression and Function

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Neurexins are diffusely distributed in neurons and become concentrated at presynaptic terminals as neurons mature. There exists a trans-synaptic dialog between neurexin and neuroligin, meaning neuroligin can induce the expression of neurexin and vise versa. [3] This bi-directional trigger aids in the formation of synapses and is a key component to modifying the neuronal network. Over-expression of either of these proteins causes an increase in synapse forming sites, thus providing evidence that neurexin plays a functional role in synaptogenesis. [4] Conversely, the blocking of β-neurexin interactions reduces the number of excitatory and inhibitory synapses. It is not clear how exactly neurexin promotes the formation of synapses. One possibility is that actin is polymerized on the tail end of β-neurexin, which traps and stabilizes accumulating synaptic vesicles. This forms a forward feeding cycle, where small clusters of β-neurexins recruit more β-neurexins and scaffolding proteins to form a large synaptic adhesive contact.[4]


neurexin
Identifiers
OrganismDrosophila melanogaster
SymbolNrx-IV
Entrez39387
RefSeq (mRNA)NM_168491.3
RefSeq (Prot)NP_524034.2
UniProtQ94887
Other data
Chromosome3L: 12.14 - 12.15 Mb
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StructuresSwiss-model
DomainsInterPro
neurexin
Identifiers
OrganismMus musculus
SymbolNrxn1
Entrez18189
RefSeq (mRNA)NM_177284.2
RefSeq (Prot)NP_064648.3
UniProtQ9CS84
Other data
Chromosome17: 90.03 - 91.09 Mb
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StructuresSwiss-model
DomainsInterPro
The trans-synaptic dialog between neurexin and neuroligin organizes the apposition of pre- and post-synaptic machinery by recruiting scaffolding proteins and other synaptic elements such as NMDA receptors, CASK, and synaptotagmin, all of which are necessary for a synapse to exist.

References

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  1. ^ Craig AM, Kang Y (February 2007). "Neurexin-neuroligin signaling in synapse development". Curr. Opin. Neurobiol. 17 (1): 43–52. doi:10.1016/j.conb.2007.01.011. PMC 2820508. PMID 17275284.{{cite journal}}: CS1 maint: date and year (link)
  2. ^ Craig AM, Kang Y (February 2007). "Neurexin-neuroligin signaling in synapse development". Curr. Opin. Neurobiol. 17 (1): 43–52. doi:10.1016/j.conb.2007.01.011. PMC 2820508. PMID 17275284.{{cite journal}}: CS1 maint: date and year (link)
  3. ^ Knight D, Xie W, Boulianne GL (December 2011). "Neurexins and neuroligins: recent insights from invertebrates". Mol. Neurobiol. 44 (3): 426–40. doi:10.1007/s12035-011-8213-1. PMC 3229692. PMID 22037798.{{cite journal}}: CS1 maint: date and year (link) CS1 maint: multiple names: authors list (link)
  4. ^ a b Dean C, Dresbach T (January 2006). "Neuroligins and neurexins: linking cell adhesion, synapse formation and cognitive function". Trends Neurosci. 29 (1): 21–9. doi:10.1016/j.tins.2005.11.003. PMID 16337696.{{cite journal}}: CS1 maint: date and year (link)