View source for 1jl4

[[Image:1jl4.gif|left|200px]]<br />
<applet load="1jl4" size="450" color="white" frame="true" align="right" spinBox="true" 
caption="1jl4, resolution 4.3&Aring;" />
'''CRYSTAL STRUCTURE OF THE HUMAN CD4 N-TERMINAL TWO DOMAIN FRAGMENT COMPLEXED TO A CLASS II MHC MOLECULE'''<br />

==Overview==
The structural basis of the interaction between the CD4 coreceptor and a, class II major histocompatibility complex (MHC) is described. The crystal, structure of a complex containing the human CD4 N-terminal two-domain, fragment and the murine I-A(k) class II MHC molecule with associated, peptide (pMHCII) shows that only the "top corner" of the CD4 molecule, directly contacts pMHCII. The CD4 Phe-43 side chain extends into a, hydrophobic concavity formed by MHC residues from both alpha 2 and beta 2, domains. A ternary model of the CD4-pMHCII-T-cell receptor (TCR) reveals, that the complex appears V-shaped with the membrane-proximal pMHCII at the, apex. This configuration excludes a direct TCR-CD4 interaction and, suggests how TCR and CD4 signaling is coordinated around the antigenic, pMHCII complex. Human CD4 binds to HIV gp120 in a manner strikingly, similar to the way in which CD4 interacts with pMHCII. Additional contacts, between gp120 and CD4 give the CD4-gp120 complex a greater affinity. Thus, ligation of the viral envelope glycoprotein to CD4 occludes the, pMHCII-binding site on CD4, contributing to immunodeficiency.

==About this Structure==
1JL4 is a [http://en.wikipedia.org/wiki/Protein_complex Protein complex] structure of sequences from [http://en.wikipedia.org/wiki/Gallus_gallus Gallus gallus], [http://en.wikipedia.org/wiki/Homo_sapiens Homo sapiens] and [http://en.wikipedia.org/wiki/Mus_musculus Mus musculus]. Full crystallographic information is available from [http://ispc.weizmann.ac.il/oca-bin/ocashort?id=1JL4 OCA]. 

==Reference==
Crystal structure of the human CD4 N-terminal two-domain fragment complexed to a class II MHC molecule., Wang JH, Meijers R, Xiong Y, Liu JH, Sakihama T, Zhang R, Joachimiak A, Reinherz EL, Proc Natl Acad Sci U S A. 2001 Sep 11;98(19):10799-804. Epub 2001 Sep 4. PMID:[http://ispc.weizmann.ac.il//pmbin/getpm?pmid=11535811 11535811]
[[Category: Gallus gallus]]
[[Category: Homo sapiens]]
[[Category: Mus musculus]]
[[Category: Protein complex]]
[[Category: Meijers, R.]]
[[Category: Reinherz, E.L.]]
[[Category: Wang, J.H.]]
[[Category: protein-protein complex]]

''Page seeded by [http://ispc.weizmann.ac.il/oca OCA ] on Thu Nov  8 14:12:49 2007''