Sandbox207
From Proteopedia
This page is reserveted for a work from two students in ESBS (A.Butet and E.Rosati) Thanks.
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| 1gnh, resolution 3.00Å () | |||||||||
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| Resources: | FirstGlance, OCA, RCSB, PDBsum | ||||||||
| Coordinates: | save as pdb, mmCIF, xml | ||||||||
C-reactive protein, CRP
Image:Image2.jpg
CRP structure
Contents |
Structure
Gene structure, family
- The CRP gene is located on chromosome 1q23. It is composed of two exons and one intron. This gene is regulated by interleukin-6, the principal inducer of the gene during the acute phase. CRP is secreted by hepatocytes.
- The Human CRP belongs to the pentraxin family of proteins having five identical, non-covalently associated subunits that form a symmetrical homopentameric ring. The pentraxin family is highly conserved in evolution.
Size
- Each subunit contains 206 amino acid residues (approximately 23kDa) and is non-glycosylated. The outside diameter of the pentamer is 102 Å, the diameter of the inner core is 30 Å, and the diameter of the protomer is 36 Å.
Detailed strucutre
- Each promoter consists of two anti-parallel β sheets (the lectin fold) with an α helix on the effector face of the protein. The ligand biding site is located on the concave face of the protein, and is composed of loops with 2 calcium ions bound 4 Å apart by protein side-chains.
- The recognition face contains the which consists of two coordinated calcium ions next to a hydrophobic pocket in which the phosphocholine stays.
- There are interpromoter interactions between the subunits: three salt bridges are included and the 115-123 loop of one protomer and the 40-42 and 197-202 regions of adjacent protomers are involved. Moreover, the subunits are capable to rotate by 15-20° around an axis parallel to the central alpha-helix.
- Thanks to this rotation, the alpha-helices can lie closer to the axis of the pentamere, therefore bringin the bound Ca2+ further away from it. On each subunit, we can find phosphocholine bound in a shallow surface pocket. With the help of phosphate groups and Glu81 via the choline moiety, the phosphocholine can interact with the two protein-bound ions.
