3D domain swapping in a chimeric c-Src SH3 domain takes place through two hinge loops.
Camara-Artigas, A., Martinez-Rodriguez, S., Ortiz-Salmeron, E., Martin-Garcia, J.M.(2014) J Struct Biol 186: 195-203
- PubMed: 24556574 
- DOI: https://doi.org/10.1016/j.jsb.2014.02.007
- Primary Citation of Related Structures:  
4LE9 - PubMed Abstract: 
In the Src Homology 3 domain (SH3) the RT and n-Src loops form a pocket that accounts for the specificity and affinity in binding of proline rich motifs (PRMs), while the distal and diverging turns play a key role in the folding of the protein. We have solved the structure of a chimeric mutant c-Src-SH3 domain where specific residues at the RT- and n-Src-loops have been replaced by those present in the corresponding Abl-SH3 domain. Crystals of the chimeric protein show a single molecule in the asymmetric unit, which appears in an unfolded-like structure that upon generation of the symmetry related molecules reveals the presence of a domain swapped dimer where both, RT- and n-Src loops, act as hinge loops. In contrast, the fold of the diverging type II β-turn and the distal loop are well conserved. Our results are the first evidence for the presence of a structured diverging type II β-turn in an unfolded-like intermediate of the c-Src-SH3 domain, which can be stabilized by interactions from the β-strands of the same polypeptide chain or from a neighboring one. Futhermore, this crystallographic structure opens a unique opportunity to study the effect of the amino acid sequence of the hinge loops on the 3D domain swapping process of c-Src-SH3.
Organizational Affiliation: 
Department of Chemistry and Physics, Research Centre for Agricultural and Food Biotechnology (BITAL), University of Almería, Agrifood Campus of International Excellence (ceiA3), Carretera de Sacramento, Almería 04120, Spain. Electronic address: acamara@ual.es.