Sandbox Reserved 1121: Difference between revisions

Line 14:

Each subunit consists of two antiparallel <scene name='71/719862/Sheet/1'>β-sheets</scene><ref name="uniprot"/> with a flattened jellyroll topology<ref name="Volanakis"/> and a long <scene name='71/719862/Helix/1'>α-helix</scene> (residues 168-176) that lies folded against the β-sheets. The predominant structure is β-sheet<ref>PMID: 1382589</ref> but short helical regions can be noticed for the residues 43 and 185<ref name="kumar"/>. The carboxyl terminal end of the helix along with the loop 177-182 forms one of the two sides of a cleft that extends from the centre of the protomer to its edge at the central pore of the pentamer<ref name="Volanakis"/>. The other side of the cleft is formed of parts of the amino and carboxyl termini of the protomer<ref name="Volanakis"/>. This furrow is 24 Å long, 7.5 Å deep and 12.4 Å wide. The side walls are constructed from Ser5, Arg6, Gln203, Pro206, Trp187, Arg188, Asn160, Gly177, Leu176, Tyr175, His95 and Asp112<ref name="Thompson"/>. This cleft is involved in C1q binding and perhaps also with the neutrophils Fc Receptor<ref name="duclos">PMID: 15531769 </ref><ref name="Volanakis"/>.The outer part of the furrow is positively charged but the inner part terminates halfway through the pentamer pore at residue Asp112, providing a ring of negative charges lining the pore<ref name="Thompson"/>. Asp112 seems to be an important residue for recognition of Cq1 by CRP<ref name="Thompson"/> because it is considered, with Tyr175, to be C1q contact residues. Glu88 seems to influence the conformational change of C1q necessary for complement activation, while Asn158 and His38 may contribute to the correct geometry of the binding site<ref name="Volanakis"/>.

On the other face of the protomer (face A), two calcium ions are bound 4 Å apart by protein sidechains coming from loops collected at the concave face (face B) and ~~this is~~ the site ~~of ligand binding~~<ref name="Thompson"/>. Each subunit in CRP is rotated by 22° towards the fivefold axis such that the helices of face A are 5 Å closer to the axis and the calcium sites on face B move away by an equivalent amount<ref name="Volanakis"/><ref name="Thompson"/>.

The cleft that binds C1q and Fc-Receptor is on the face A of a CRP protomer. On the other face of the protomer (face B), two calcium ions are bound 4 Å apart by protein sidechains coming from loops collected at the concave face (face A). The calcium ion and the loop on the face B form the phosphocholine (PC)-binding site<ref name="Thompson"/>. Each subunit in CRP is rotated by 22° towards the fivefold axis such that the helices of face A are 5 Å closer to the axis and the calcium sites on face B move away by an equivalent amount<ref name="Volanakis"/><ref name="Thompson"/>.

Thus, CRP pentamer has two faces: a face that exibit the five phosphocholine binding sites and a face involve in the binding of C1q and possibly FcR <ref name="Volanakis"/>.

Sandbox Reserved 1121: Difference between revisions

Navigation menu

Page actions

Page actions

Personal tools

Navigation

Search

Tools

@@ Line 14: / Line 14: @@
 Each subunit consists of two antiparallel <scene name='71/719862/Sheet/1'>β-sheets</scene><ref name="uniprot"/> with a flattened jellyroll topology<ref name="Volanakis"/> and a long <scene name='71/719862/Helix/1'>α-helix</scene> (residues 168-176) that lies folded against the β-sheets. The predominant structure is β-sheet<ref>PMID: 1382589</ref> but short helical regions can be noticed for the residues 43 and 185<ref name="kumar"/>. The carboxyl terminal end of the helix along with the loop 177-182 forms one of the two sides of a cleft that extends from the centre of the protomer to its edge at the central pore of the pentamer<ref name="Volanakis"/>. The other side of the cleft is formed of parts of the amino and carboxyl termini of the protomer<ref name="Volanakis"/>. This furrow is 24 Å long, 7.5 Å deep and 12.4 Å wide. The side walls are constructed from Ser5, Arg6, Gln203, Pro206, Trp187, Arg188, Asn160, Gly177, Leu176, Tyr175, His95 and Asp112<ref name="Thompson"/>. This cleft is involved in C1q binding and perhaps also with the neutrophils Fc Receptor<ref name="duclos">PMID: 15531769 </ref><ref name="Volanakis"/>.The outer part of the furrow is positively charged but the inner part terminates halfway through the pentamer pore at residue Asp112, providing a ring of negative charges lining the pore<ref name="Thompson"/>. Asp112 seems to be an important residue for recognition of Cq1 by CRP<ref name="Thompson"/> because it is considered, with Tyr175, to be C1q contact residues. Glu88 seems to influence the conformational change of C1q necessary for complement activation, while Asn158 and His38 may contribute to the correct geometry of the binding site<ref name="Volanakis"/>.
-On the other face of the protomer (face A), two calcium ions are bound 4 Å apart by protein sidechains coming from loops collected at the concave face (face B) and this is the site of ligand binding<ref name="Thompson"/>. Each subunit in CRP is rotated by 22° towards the fivefold axis such that the helices of face A are 5 Å closer to the axis and the calcium sites on face B move away by an equivalent amount<ref name="Volanakis"/><ref name="Thompson"/>.
+The cleft that binds C1q and Fc-Receptor is on the face A of a CRP protomer. On the other face of the protomer (face B), two calcium ions are bound 4 Å apart by protein sidechains coming from loops collected at the concave face (face A). The calcium ion and the loop on the face B form the phosphocholine (PC)-binding site<ref name="Thompson"/>. Each subunit in CRP is rotated by 22° towards the fivefold axis such that the helices of face A are 5 Å closer to the axis and the calcium sites on face B move away by an equivalent amount<ref name="Volanakis"/><ref name="Thompson"/>.
 Thus, CRP pentamer has two faces: a face that exibit the five phosphocholine binding sites and a face involve in the binding of C1q and possibly FcR <ref name="Volanakis"/>.