Journal:JBIC:3
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| - | <scene name='Journal:JBIC:3/Opening/2'>S100A16</scene> is a special member of the S100 class of <scene name='Journal:JBIC:3/Binding_calcium/5'>calcium binding</scene> proteins, because it <scene name='Journal:JBIC:3/Ca_binding_no_change/1'>does not perform a significant conformational change</scene> upon calcium(II) binding. This was observed after determination of the solution structures of apo and calcium(II)-bound S100A16 and the crystal structure of apo S100A16. The likely reason for minimal conformational change <scene name='Journal:JBIC:3/ | + | <scene name='Journal:JBIC:3/Opening/2'>S100A16</scene> is a special member of the S100 class of <scene name='Journal:JBIC:3/Binding_calcium/5'>calcium binding</scene> proteins, because it <scene name='Journal:JBIC:3/Ca_binding_no_change/1'>does not perform a significant conformational change</scene> upon calcium(II) binding. This was observed after determination of the solution structures of apo and calcium(II)-bound S100A16 and the crystal structure of apo S100A16. The likely reason for minimal conformational change <<scene name='Journal:JBIC:3/Calcium_binding_start/7'>in S100A16</scene> is the lower calcium binding affinity and <scene name='Journal:JBIC:3/Hydrophobic_residues/2'>stronger hydrophobic interaction between helix III and IV</scene> present in this protein with respect to other S100 proteins. Another characteristic of <scene name='Journal:JBIC:3/Opening/3'>S100A16</scene> is that the helix IV has the <scene name='Journal:JBIC:3/Apo_length/2'>same length in both apo</scene> and <scene name='Journal:JBIC:3/Length_ca/2'>calcium(II) forms</scene> because <scene name='Journal:JBIC:3/Gly-gly-ile-thr-gly-pro/1'>of the presence</scene> of a <scene name='Journal:JBIC:3/Gly-gly-ile-thr-gly-pro_zoom/1'>Gly-Gly-Ile-Thr-Gly-Pro sequence motif</scene>. Based on the available structures of S100 members, we analyzed and summarized all their conformational changes due to calcium(II) binding by a principal component analysis. <scene name='Journal:JBIC:3/Calcium_binding_start/6'>Calcium binding</scene> was proved by both NMR titration and Isothermal Titration Calorimetry (ITC) experiments. Even if the <scene name='Journal:JBIC:3/Gly_without/4'>important Glu residue in the last position of first EF-hand calcium binding loop is missing</scene>, these experimental data indicated that S100A16 can <scene name='Journal:JBIC:3/Gly_without_full/3'>still bind one calcium(II) ion in such loop</scene>. NMR relaxation <scene name='Journal:JBIC:3/Flexible_broadwide/2'>studies showed that the first calcium binding loop and the beginning of the second helix</scene> are the most <scene name='Journal:JBIC:3/Flexible_broad/2'>flexible regions in both the apo and calcium(II)-bound S100A16</scene>. Although the biological function of S100A16 is still unclear yet, these structural and dynamic properties can provide useful information for further functional studies. |
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Revision as of 07:48, 31 October 2010
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Structural characterization of human S100A16, a low-affinity calcium binder
Elena Babini • Ivano Bertini • Valentina Borsi • Vito Calderone • Xiaoyu Hu • Claudio Luchinat • Giacomo Parigi[1]
Molecular Tour
is a special member of the S100 class of proteins, because it upon calcium(II) binding. This was observed after determination of the solution structures of apo and calcium(II)-bound S100A16 and the crystal structure of apo S100A16. The likely reason for minimal conformational change < is the lower calcium binding affinity and present in this protein with respect to other S100 proteins. Another characteristic of is that the helix IV has the and because of a . Based on the available structures of S100 members, we analyzed and summarized all their conformational changes due to calcium(II) binding by a principal component analysis. was proved by both NMR titration and Isothermal Titration Calorimetry (ITC) experiments. Even if the , these experimental data indicated that S100A16 can . NMR relaxation are the most . Although the biological function of S100A16 is still unclear yet, these structural and dynamic properties can provide useful information for further functional studies.
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