Talk:Sandbox Reserved 823: Difference between revisions
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The SNARE domain is approximately '''60-70 residues''' long and is located immediately adjacent to a C-terminal transmembrane anchor. It contains a r'''epeating heptad pattern of hydrophobic residues'''. Their orientation places them in an '''alpha-helical structure''' so that all the hydrophobic side chains are located on the '''same face''' of the helix.<ref name="anto" /><ref> PMID: 9731768 </ref><ref name="sutton" /> SNARE domains allow the four SNAREs protein to assemble into '''parallel four-helix bundles'''. This parallel arrangement brings the transmembrane anchors and the membranes closer. <ref> PMID: 9267032 </ref> | The SNARE domain is approximately '''60-70 residues''' long and is located immediately adjacent to a C-terminal transmembrane anchor. It contains a r'''epeating heptad pattern of hydrophobic residues'''. Their orientation places them in an '''alpha-helical structure''' so that all the hydrophobic side chains are located on the '''same face''' of the helix.<ref name="anto" /><ref> PMID: 9731768 </ref><ref name="sutton" /> SNARE domains allow the four SNAREs protein to assemble into '''parallel four-helix bundles'''. This parallel arrangement brings the transmembrane anchors and the membranes closer. <ref> PMID: 9267032 </ref> | ||
=== '' “0”-layers'' === | === '' “0”-layers'' === | ||
[[Image:Layers.png|thumbnail||800 px||left| '''Topology of the 16 layers of the SNARE complex.''']] | [[Image:Layers.png|thumbnail||800 px||left| '''Topology of the 16 layers of the SNARE complex.''']] | ||
The centre of the four-helix bundle is constituted of '''16 layers'''. These layers are composed of '''hydrophobic side chains''', which are perpendicular to the axis of the four-helix bundle, except for the central '''“0”-layer'''. This last one consists of '''three glutamine (Q)''' and '''one arginine (R)''' highly conserved residues. Those highly conserved residues have led to a new classification of SNAREs into '''Q- and R-SNAREs'''. <ref> PMID: 9861047 </ref> Almost all membrane fusion reactions require one R-SNARE and three Q-SNAREs:Qa, Qb and Qc.<ref> PMID: 11237004 </ref><ref> PMID: 11001046 </ref> In many cases, the R-SNARE is in the vesicle, and the three Q-SNAREs are in the target membrane. For the early endosomal SNARE complex, syntaxin 13, vti1a, syntaxin 6, and VAMP4 were respectively classified as Qa-, Qb-, Qc- and R-SNAREs. | The centre of the four-helix bundle is constituted of '''16 layers'''. These layers are composed of '''hydrophobic side chains''', which are perpendicular to the axis of the four-helix bundle, except for the central '''“0”-layer'''. This last one consists of '''three glutamine (Q)''' and '''one arginine (R)''' highly conserved residues. Those highly conserved residues have led to a new classification of SNAREs into '''Q- and R-SNAREs'''. <ref> PMID: 9861047 </ref> Almost all membrane fusion reactions require one R-SNARE and three Q-SNAREs:Qa, Qb and Qc.<ref> PMID: 11237004 </ref><ref> PMID: 11001046 </ref> In many cases, the R-SNARE is in the vesicle, and the three Q-SNAREs are in the target membrane. For the early endosomal SNARE complex, syntaxin 13, vti1a, syntaxin 6, and VAMP4 were respectively classified as Qa-, Qb-, Qc- and R-SNAREs. | ||
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[[Image:Snare_complex.jpg|thumbnail||600 px|| | [[Image:Snare_complex.jpg|thumbnail||600 px||center| '''Crystal structure of the early endosomal SNARE complex.''' | ||
(A) Backbone overlay of the early endosomal SNARE complex (in color) and the neuronal SNARE complex (gray). | (A) Backbone overlay of the early endosomal SNARE complex (in color) and the neuronal SNARE complex (gray). | ||
(B) N- to C-terminal view of the 0 layer containing the unusual aspartate in vti1a. (Color, early endosomal SNARE complex; gray, neuronal SNARE complex.) | (B) N- to C-terminal view of the 0 layer containing the unusual aspartate in vti1a. (Color, early endosomal SNARE complex; gray, neuronal SNARE complex.) | ||
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== ''' SNAREs | == ''' SNAREs and pulmonary hypertension ''' == | ||
'''Pulmonary hypertension''' (PH) corresponds to an '''increase of blood pressure''' in the pulmonary artery, pulmonary vein, or pulmonary capillaries leading to shortness of breath, dizziness, fainting, leg swelling and other symptoms. Pulmonary hypertension can be a '''severe disease''', characterized by a decreased exercise tolerance and heart failure. The origin of the disease seems to be a golgi-dysfunction. Indeed, dysfunction of golgi tethers, SNAPs and '''SNAREs''' apparently leads to pulmonary hypertension.<ref> PMID:17416597 </ref> | '''Pulmonary hypertension''' (PH) corresponds to an '''increase of blood pressure''' in the pulmonary artery, pulmonary vein, or pulmonary capillaries leading to shortness of breath, dizziness, fainting, leg swelling and other symptoms. Pulmonary hypertension can be a '''severe disease''', characterized by a decreased exercise tolerance and heart failure. The origin of the disease seems to be a golgi-dysfunction. Indeed, dysfunction of golgi tethers, SNAPs and '''SNAREs''' apparently leads to pulmonary hypertension.<ref> PMID:17416597 </ref> | ||