1ywp: Difference between revisions

[[Image:1ywp.gif|left|200px]]<br /><applet load="1ywp" size="350" color="white" frame="true" align="right" spinBox="true"  

The enzyme phospholipase Cgamma1 (PLCgamma1) is essential for T cell signaling and activation. Following T cell receptor ligation, PLCgamma1 interacts through its SH2 and SH3 domains with the adaptors LAT and SLP-76, respectively, to form a multiprotein signaling complex that leads to activation of PLCgamma1 by Syk tyrosine kinases. To identify the binding site for PLCgamma1 in SLP-76, we used isothermal titration calorimetry to measure affinities for the interaction of PLCgamma1-SH3 with a set of overlapping peptides spanning the central proline-rich region of SLP-76. PLCgamma1-SH3 bound with high specificity to the SLP-76 motif 186PPVPPQRP193, which represents the minimal binding site. To understand the basis for selective recognition, we determined the crystal structures of PLCgamma1-SH3 in free form, and bound to a 10-mer peptide containing this site, to resolutions of 1.60 A and 1.81 A, respectively. The structures reveal that several key contacting residues of the SH3 shift toward the SLP-76 peptide upon complex formation, optimizing the fit and strengthening hydrophobic interactions. Selectivity results mainly from strict shape complementarity between protein and peptide, rather than sequence-specific hydrogen bonding. In addition, Pro193 of SLP-76 assists in positioning Arg192 into the compass pocket of PLCgamma1-SH3, which coordinates the compass residue through an unusual aspartate. The PLCgamma1-SH3/SLP-76 structure provides insights into ligand binding by SH3 domains related to PLCgamma1-SH3, as well as into recognition by PLCgamma1 of signaling partners other than SLP-76.

1YWP is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Rattus_norvegicus Rattus norvegicus]. Active as [http://en.wikipedia.org/wiki/Phosphoinositide_phospholipase_C Phosphoinositide phospholipase C], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=3.1.4.11 3.1.4.11] Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1YWP OCA].  

[[Category: Mariuzza, R A.]]

[[Category: Swaminathan, C P.]]

[[Category: Velikovsky, C A.]]

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