Parvin: Difference between revisions
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Alpha-parvin's structure can be divided into four regions: 1) N-terminal flexible domain (residues 1-96), 2) N-terminal CH domain (97-200 according to SMART<ref>PMID: 9600884</ref>), 3) linker region (201-241) and 4) C-terminal CH domain (242-372 identified by limited subtilisin proteolysis<ref>PMID: 18940607</ref>). Most interactions of alpha-parvin are mapped to the C-terminal CH domain, but CdGAP and perhaps alphaPIX or other, yet unknown partners, interact with the N-terminal flexibile domain. This flexible domain seems to lack a well defined 3D structure and can therefore be classified as a putative [[Intrinsically Disordered Protein|intrinsically disordered]] region. The interactions of this regions with the binding partners are therefore likely to be characterized by relatively low affinity, but high affinity nonetheless.<ref>PMID: 19265676</ref> The abovementioned phosphorylation sites (serines 4 and 8) involved in focal adhesion regulation are located in this segment, which makes them so called disorder-enhanced phosphorylation sites.<ref>PMID: 14960716</ref><ref>PMID: 18388127</ref> | Alpha-parvin's structure can be divided into four regions: 1) N-terminal flexible domain (residues 1-96), 2) N-terminal CH domain (97-200 according to SMART<ref>PMID: 9600884</ref>), 3) linker region (201-241) and 4) C-terminal CH domain (242-372 identified by limited subtilisin proteolysis<ref>PMID: 18940607</ref>). Most interactions of alpha-parvin are mapped to the C-terminal CH domain, but CdGAP and perhaps alphaPIX or other, yet unknown partners, interact with the N-terminal flexibile domain. This flexible domain seems to lack a well defined 3D structure and can therefore be classified as a putative [[Intrinsically Disordered Protein|intrinsically disordered]] region. The interactions of this regions with the binding partners are therefore likely to be characterized by relatively low affinity, but high affinity nonetheless.<ref>PMID: 19265676</ref> The abovementioned phosphorylation sites (serines 4 and 8) involved in focal adhesion regulation are located in this segment, which makes them so called disorder-enhanced phosphorylation sites.<ref>PMID: 14960716</ref><ref>PMID: 18388127</ref> | ||
<Structure load='2vzc' scene=' | <Structure load='2vzc' scene='Alpha-parvin/Parvin/9' size='340' frame='true' align='left' caption='Structure of the C-terminal CH domain([[2vzc]])'/> | ||
===C-terminal CH domain=== | ===C-terminal CH domain=== | ||
The calponin-homology (CH) domains are helical structural units around 100 amino acids long. They comprise at least four helices, three of them forming a helical bundle. CH domains usually comprise elements of big multidomain proteins and are present either in singlet<ref>PMID: 19459066</ref> or duplex/tandem arrangement.<ref>PMID: 19565353</ref> The tandem arrangement of CH domains is often associated with F-actin binding<ref>PMID: 9708889</ref><ref>PMID: 18952167</ref> (and is thus called actin-binding domain or ABD), but generally CH domains seem to be characterized by functional plasticity and ability to bind various structural motifs.<ref>PMID: 11911887</ref> In the case of alpha-parvin, the interactions of CH domains with both F-actin and other partners (paxillin, ILK) are observed. The interactions with paxillin and ILK are mediated by a single CH domain, the C-terminal one. This domain has attracted most attention. While no full-length structure of alpha-parvin has been solved to date, the structure of the C-terminal CH domain, on its own<ref>PMID: 18940607</ref> and in complexes (with paxillin<ref>PMID: 18940607</ref><ref>PMID: 18508764</ref> and the pseudokinase domain of ILK<ref>PMID: 20005845</ref>) are available. | The calponin-homology (CH) domains are helical structural units around 100 amino acids long. They comprise at least four helices, three of them forming a helical bundle. CH domains usually comprise elements of big multidomain proteins and are present either in singlet<ref>PMID: 19459066</ref> or duplex/tandem arrangement.<ref>PMID: 19565353</ref> The tandem arrangement of CH domains is often associated with F-actin binding<ref>PMID: 9708889</ref><ref>PMID: 18952167</ref> (and is thus called actin-binding domain or ABD), but generally CH domains seem to be characterized by functional plasticity and ability to bind various structural motifs.<ref>PMID: 11911887</ref> In the case of alpha-parvin, the interactions of CH domains with both F-actin and other partners (paxillin, ILK) are observed. The interactions with paxillin and ILK are mediated by a single CH domain, the C-terminal one. This domain has attracted most attention. While no full-length structure of alpha-parvin has been solved to date, the structure of the C-terminal CH domain, on its own<ref>PMID: 18940607</ref> and in complexes (with paxillin<ref>PMID: 18940607</ref><ref>PMID: 18508764</ref> and the pseudokinase domain of ILK<ref>PMID: 20005845</ref>) are available. | ||
[[Image:Consurf_key_small.gif|right|200px]]The scene on the left shows the structure of the <scene name=' | [[Image:Consurf_key_small.gif|right|200px]]The scene on the left shows the structure of the <scene name='Alpha-parvin/Parvin/9'>C-terminal CH domain of alpha-parvin</scene> at around 1.05 Å ([[2vzc]]). When a sequence alignment of alpha-parvin with all its sequence homologues is performed and the protein is coloured according to <scene name='User:Marcin_Jozef_Suskiewicz/Sandbox_Parvin//Parvin/3'>the degree of sequence conservation</scene>, one can see that the highest degree of conservation is exhibited by the residues located in <scene name='User:Marcin_Jozef_Suskiewicz/Sandbox_Parvin//Parvin/5'>the core helices</scene>, while the residues in linker helices and loops are less conserved. When the <scene name='User:Marcin_Jozef_Suskiewicz/Sandbox_Parvin//Parvin_overlap/1'>structural superposition</scene> of the <font color='brown'>C-terminal CH domain of alpha-parvin</font> and <font color='DimGrey'>one of the CH domains of alpha-actinin 3</font> ([[1wku]]) is performed, a good overall overlap is observed, as represented by the RMSD of 1.19 Å for 103 equivalent C<sup>α</sup> positions, despite low sequence homology (≤26% identity).<ref>PMID: 18940607</ref> Again the best overlap is seen for the core helices. This suggests that the structural framework of CH domain and its core in particular are quite robust under evolution. | ||
The most diverged fragments in the C-terminal CH domain of alpha-parvin correspond to 1) an <scene name='User:Marcin_Jozef_Suskiewicz/Sandbox_Parvin//Parvin_overlap/3'>additional helix</scene> (so called N-terminal linker helix; it is labelled αN | The most diverged fragments in the C-terminal CH domain of alpha-parvin correspond to 1) an <scene name='User:Marcin_Jozef_Suskiewicz/Sandbox_Parvin//Parvin_overlap/3'>additional helix</scene> (so called N-terminal linker helix; it is labelled αN or helix N) located at the N-terminal end of the domain and not observed in any other CH domain and 2) a <scene name='User:Marcin_Jozef_Suskiewicz/Sandbox_Parvin//Parvin_overlap/5'>long loop</scene> between two helices (αC and αE). One could ask whether the N-terminal linker helix is an integral part of the C-terminal CH domain or just a part of a linker region between the two CH domains. The fact that it interacts strongly with the core helices by means of both electrostatic (<scene name='Alpha-parvin/Parvin_overlap/1'>residues D248, D251 and D255 with K355 and R359</scene>) and hydrophobic (<scene name='Alpha-parvin/Parvin_overlap/4'>residues F250, L253 and F254 with L354, K355, L358, R359, K260 and L261</scene>) interactions suggests that it is indeed integral to the domain. The long loop mentioned above contains a <scene name='User:Marcin_Jozef_Suskiewicz/Sandbox_Parvin//Parvin_overlap/6'>3-amino acid insertion</scene> (313-315) relative to other known CH domains and differs in conformation between different structures of alpha-parvin, suggesting it is relatively flexible.<ref>PMID: 18940607</ref> Interestingly, these two regions, the N-terminal linker helix and the long loop, are involved in binding of alpha-parvin to its binding partners, paxillin and ILK respectively. | ||
<Structure load='Complex_parvin.pdb' size='340' scene='Alpha-parvin/Parvin/2' frame='true' align='right' caption='The alignment of three C-terminal CH domains of alpha-parvin bound to different paxillin LD motifs ([[2vzd]], [[2vzg]], [[2vzi]])'/> | <Structure load='Complex_parvin.pdb' size='340' scene='Alpha-parvin/Parvin/2' frame='true' align='right' caption='The alignment of three C-terminal CH domains of alpha-parvin bound to different paxillin LD motifs ([[2vzd]], [[2vzg]], [[2vzi]])'/> | ||