View source for 1qok


==MFE-23 AN ANTI-CARCINOEMBRYONIC ANTIGEN SINGLE-CHAIN FV ANTIBODY==
<StructureSection load='1qok' size='340' side='right'caption='[[1qok]], [[Resolution|resolution]] 2.40&Aring;' scene=''>
== Structural highlights ==
<table><tr><td colspan='2'>[[1qok]] is a 1 chain structure with sequence from [https://en.wikipedia.org/wiki/Mus_musculus Mus musculus]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1QOK OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=1QOK FirstGlance]. <br>
</td></tr><tr id='method'><td class="sblockLbl"><b>[[Empirical_models|Method:]]</b></td><td class="sblockDat" id="methodDat">X-ray diffraction, [[Resolution|Resolution]] 2.4&#8491;</td></tr>
<tr id='resources'><td class="sblockLbl"><b>Resources:</b></td><td class="sblockDat"><span class='plainlinks'>[https://proteopedia.org/fgij/fg.htm?mol=1qok FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=1qok OCA], [https://pdbe.org/1qok PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=1qok RCSB], [https://www.ebi.ac.uk/pdbsum/1qok PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=1qok ProSAT]</span></td></tr>
</table>
== Function ==
[https://www.uniprot.org/uniprot/Q8K1F2_MOUSE Q8K1F2_MOUSE] 
<div style="background-color:#fffaf0;">
== Publication Abstract from PubMed ==
MFE-23 is the first single-chain Fv antibody molecule to be used in patients and is used to target colorectal cancer through its high affinity for carcinoembryonic antigen (CEA), a cell-surface member of the immunoglobulin superfamily. MFE-23 contains an N-terminal variable heavy-chain domain joined by a (Gly(4)Ser)(3) linker to a variable light-chain (V(L)) domain (kappa chain) with an 11-residue C-terminal Myc-tag. Its crystal structure was determined at 2.4 A resolution by molecular replacement with an R(cryst) of 19.0%. Five of the six antigen-binding loops, L1, L2, L3, H1 and H2, conformed to known canonical structures. The sixth loop, H3, displayed a unique structure, with a beta-hairpin loop and a bifurcated apex characterized by a buried Thr residue. In the crystal lattice, two MFE-23 molecules were associated back-to-back in a manner not seen before. The antigen-binding site displayed a large acidic region located mainly within the H2 loop and a large hydrophobic region within the H3 loop. Even though this structure is unliganded within the crystal, there is an unusually large region of contact between the H1, H2 and H3 loops and the beta-sheet of the V(L) domain of an adjacent molecule (strands DEBA) as a result of intermolecular packing. These interactions exhibited remarkably high surface and electrostatic complementarity. Of seven MFE-23 residues predicted to make contact with antigen, five participated in these lattice contacts, and this model for antigen binding is consistent with previously reported site-specific mutagenesis of MFE-23 and its effect on CEA binding.

Crystal structure of the anti-(carcinoembryonic antigen) single-chain Fv antibody MFE-23 and a model for antigen binding based on intermolecular contacts.,Boehm MK, Corper AL, Wan T, Sohi MK, Sutton BJ, Thornton JD, Keep PA, Chester KA, Begent RH, Perkins SJ Biochem J. 2000 Mar 1;346 Pt 2:519-28. PMID:10677374<ref>PMID:10677374</ref>

From MEDLINE&reg;/PubMed&reg;, a database of the U.S. National Library of Medicine.<br>
</div>
<div class="pdbe-citations 1qok" style="background-color:#fffaf0;"></div>
== References ==
<references/>
__TOC__
</StructureSection>
[[Category: Large Structures]]
[[Category: Mus musculus]]
[[Category: Begent RHJ]]
[[Category: Boehm MK]]
[[Category: Chester KA]]
[[Category: Corper AL]]
[[Category: Keep PA]]
[[Category: Perkins SJ]]
[[Category: Sohi MK]]
[[Category: Sutton BJ]]
[[Category: Thornton JD]]
[[Category: Wan T]]