2i6s: Difference between revisions

[[Image:2i6s.gif|left|200px]]<br /><applet load="2i6s" size="350" color="white" frame="true" align="right" spinBox="true"  

C2a provides the catalytic center to the convertase complexes of the classical and lectin-binding pathways of complement activation. We determined two crystal structures of full-length C2a, with and without a pseudo ligand bound. Both structures reveal a near-active conformation of the catalytic center of the serine protease domains, while the von Willebrand factor A-type domains display an intermediate activation state of helix alpha7 with an open, activated metal-ion-dependent adhesion site. The open adhesion site likely serves to enhance the affinity for the ligand C4b, similar to "inside-out" signaling in integrins. Surprisingly, the N-terminal residues of C2a are buried in a crevice near helix alpha7, indicative of a structural switch between C2 and C2a. Extended loops on the protease domain possibly envelop the protruding anaphylatoxin domain of the substrate C3. Together with a putative substrate-induced completion of the oxyanion hole, this may contribute to the high substrate specificity of the convertases.

2I6S is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Homo_sapiens Homo sapiens] with <scene name='pdbligand=NAG:'>NAG</scene> as [http://en.wikipedia.org/wiki/ligand ligand]. Active as [http://en.wikipedia.org/wiki/Classical-complement-pathway_C3/C5_convertase Classical-complement-pathway C3/C5 convertase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=3.4.21.43 3.4.21.43] Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=2I6S OCA].  

[[Category: Daha, M R.]]

[[Category: Huizinga, E G.]]

[[Category: Milder, F J.]]

[[Category: Raaijmakers, H C.A.]]

[[Category: Romijn, R A.]]

[[Category: Vandeputte, D A.A.]]

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