Sandbox Reserved 1093: Difference between revisions

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<scene name='82/829346/Lrrtm2/3'>LRRTM2</scene> is a transmembrane protein that can be found in human neurons. It functions as postsynaptic organizers that induce excitatory synapses. LRRTM2 is prominently expressed in deep layers, rather than superficial layers, of the cerebral cortex. LRRTM2 specifically localizes in excitatory synapses, and not in inhibitory synapses. In addition, LRRTMs interact with neurexins[http://proteopedia.org/wiki/index.php/Neurexin]to bridge the synaptic cleft.  
<scene name='82/829346/Lrrtm2/3'>LRRTM2</scene> is a transmembrane protein that can be found in human neurons. It functions as postsynaptic organizers that induce excitatory synapses. LRRTM2 is prominently expressed in deep layers (hippocampal neurons mostly), rather than superficial layers, of the cerebral cortex. LRRTM2 specifically localizes in excitatory synapses, and not in inhibitory synapses. In addition, LRRTMs interact with neurexins[http://proteopedia.org/wiki/index.php/Neurexin]to bridge the synaptic cleft.  


[[Image:LRRTM2+neurexin.png|1000px|left]]
[[Image:LRRTM2+neurexin.png|1000px|left]]
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== Function ==
== Function ==
LRRTM2 protein play a key role in the regulation of the synaptic fonctions and development by interracting with various proteins both inside and outside the neuron cell.


1)    Interaction with intracellular proteins
1)    Interaction with intracellular proteins


As a major regulator of excitatory synapse formation, the LRRTM2 protein plays a key role in the regulation of the postsynaptic fonctions.
It has been shown that the binding of LRRTM2 with PSD-95 on the C-term fixation site was responsible for the regulation of AMPA receptor expression. The AMPA receptors ( AMPARs) are transmembrane receptors located on the postsynaptic membrane that interact with glutamates (neurotransmittters). So, the expression of LRRTM2 in the neurons of the hippocampus have a direct link with the density of excitatory synapses. The greater the quantity of LRRTM2, the greater the density of excitatory synapses. Thus, LRRTM2 has a direct influence on the glutamatergic synaptic transmission strength.  
It has been shown that the binding between LRRTM2 and PSD-95 protein was responsible for the regulation of AMPA receptor expression. The AMPA receptors ( AMPARs) are transmembrane receptors located on the postsynaptic membrane. They are activated by the artificial glutamate AMPA which allows the transmission of the information.  So, the expression of LRRTM2 in the neurons of the hippocampus have a direct link with the density of excitatory synapses . The greater the quantity of LRRTM2, the greater the density of excitatory synapses without affecting inhibitory synapse density. So, LRRTM2 has a direct influence on the glutamatergic synaptic transmission strength.  
It has also been noted that the repression of LRRTM2 induced a decrease in the density of PSD-95. Thus, LRRTM2 recruits PSD-95 at postsynaptic density and then binds to PSD-95 via the ECFV cytoplasmic motif. The interaction of PSD-95 with glutamate receptors, located at the postsynaptic membrane, as well as with other synaptic synaptic proteins.
It has also been noted that the repression of LRRTM2 induced a decrease in the density of PSD-95. Thus, LRRTM2 recruits PSD-95 at postsynaptic density and then binds to PSD-95 via the ECFV cytoplasmic motif. The interaction of PSD-95 with glutamate receptors, located at the postsynaptic density surface, as well as with other synaptic synaptic proteins, regulates then the synaptic strength and plasticity.
By the interaction with important postsynaptic components, LRRTM2 turns out to be crucial in the regulation of the postsynaptic fonctions and plasticity.  
LRRTM2 has a direct influence on the synaptic surface expression of GLUR1 which is on of the four subunits that composed the tetramers AMPARs. This requires that LRRTM2 either directly recruits AMPA and NMPA or indirectly by recruiting PSD-95 and TARP.
By the interaction with important postsynaptic component, LRRTM2 turns out to be crucial in the regulation of the postsynaptic fonctions.  


2)    Interaction with extracellular proteins
2)    Interaction with extracellular proteins


In addition LRRT2 binds specifically to Neurexin1a and 1b. This binding plays a critical role in the formation of excitatory synapses. Without Neurexin1, LRRTM2 cannot act on presynaptic differentiation in axons. In addition, the presynaptic receptors Neurexin 1a and 1 are known to be receptors for Neurologine 1, a protein similar to LRRTM2. Neurologine 1 also regulates the formation of excitatory synapses.
On the N-term fixation site, LRRTM2 binds specifically to Neurexin1 α and β. The affinity of the binding depends on the splicing of the insert SS4 of both neurexins. This binding plays a critical role in the formation of excitatory synapses as it briges the synaptic cleft. Without Neurexin1, LRRTM2 can't act on presynaptic differentiation leading to a reduction in the amount of excitatory synapses. In addition, the presynaptic receptors Neurexin 1 α and β are known to be receptors for Neurologine 1, a protein similar to LRRTM2. Neurologine 1 also regulates the formation of excitatory synapses.




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