1ncn
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(New page: 200px<br /> <applet load="1ncn" size="450" color="white" frame="true" align="right" spinBox="true" caption="1ncn, resolution 2.70Å" /> '''the receptor-bindin...)
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Revision as of 16:13, 12 November 2007
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the receptor-binding domain of human B7-2
Overview
B7-1 and B7-2 are homologous costimulatory ligands expressed on the, surfaces of antigen-presenting cells. Their interactions with CD28/CTLA-4, receptors expressed on T cell surfaces are crucial for the proper, regulation of T cell activity. B7-1 and B7-2 display distinct roles in, immune regulation, although they are usually considered to have redundant, functions. Here, we report the crystal structure of the receptor-binding, (Ig V-type) domain of human B7-2 at 2.7-A resolution. Structures of, unliganded and liganded B7-1 and B7-2 suggest a physical-chemical basis, for the observed functional similarities and differences between these two, costimulatory ligands. Of particular note, whereas the majority of the, residues mediating B7-1 dimerization are hydrophobic, the B7-2 dimer, observed in the B7-2/CTLA-4 complex displays a very hydrophilic dimer, interface. These differences provide a mechanism for preventing the, formation of B7-1/B7-2 heterodimers. The divergence at the putative dimer, interface is also consistent with the lower tendency of B7-2 to dimerize, as shown by the monomeric state of unliganded B7-2 both in solution and, crystalline form, and may result in detailed differences in signaling, mechanisms associated with B7-1 and B7-2.
About this Structure
1NCN is a Single protein structure of sequence from Homo sapiens. Full crystallographic information is available from OCA.
Reference
Crystal structure of the receptor-binding domain of human B7-2: insights into organization and signaling., Zhang X, Schwartz JC, Almo SC, Nathenson SG, Proc Natl Acad Sci U S A. 2003 Mar 4;100(5):2586-91. Epub 2003 Feb 26. PMID:12606712
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