2rqt
From Proteopedia
Solution structure of the human DDEF1 SH3 domain
Structural highlights
FunctionASAP1_HUMAN Possesses phosphatidylinositol 4,5-bisphosphate-dependent GTPase-activating protein activity for ARF1 (ADP ribosylation factor 1) and ARF5 and a lesser activity towards ARF6. May coordinate membrane trafficking with cell growth or actin cytoskeleton remodeling by binding to both SRC and PIP2. May function as a signal transduction protein involved in the differentiation of fibroblasts into adipocytes and possibly other cell types (By similarity). Plays a role in ciliogenesis.[1] Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMedElucidation of the basis of interactions between biological molecules is essential for the understanding of living systems. Src-homology 3 (SH3) domains play critical roles in interaction networks of proteins by recognizing a proline-rich sequence motif, PxxP. There are, however, several SH3 domains that specifically bind to polypeptide chains without the conventional recognition sequence. The SH3 domain of DDEF1 associates with the SAMP motifs of the adenomatous polyposis coli (APC) tumor suppressor. The SAMP motifs are indispensable for the normal function of APC in tumor suppression. Here we present the structural basis of the interaction between the DDEF1-SH3 domain and the APC-SAMP motifs. We determined the solution structures of the DDEF1-SH3 domain both in a free state and in a complex with APC-SAMP. As the affinity of the interaction was not sufficiently high for the determination of the complex structure in solution by conventional methods, we utilized a fusion protein of the DDEF1-SH3 domain and APC-SAMP. The structures revealed that the SAMP motif adopts a class II polyproline type II helix even though it does not contain the PxxP motif and that a characteristically large hydrophobic pocket of the SH3 domain confers high selectivity to the interaction. Furthermore, investigation into the backbone dynamics of the free and bound systems by NMR spin relaxation experiments demonstrated that the DDEF1-SH3 domain exhibits high flexibility at the peptide recognition site in the absence of the ligand and that most residues of the APC-SAMP motif display extensive local motions even in the stable complex. Structural basis of the recognition of the SAMP motif of adenomatous polyposis coli by the Src-homology 3 domain.,Kaieda S, Matsui C, Mimori-Kiyosue Y, Ikegami T Biochemistry. 2010 Jun 29;49(25):5143-53. PMID:20509626[2] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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