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From Proteopedia
Crystal structure of the v-Src SH3 domain Q128R mutant
Structural highlights
FunctionSRC_CHICK Non-receptor protein tyrosine kinase which is activated following engagement of many different classes of cellular receptors including immune response receptors, integrins and other adhesion receptors, receptor protein tyrosine kinases, G protein-coupled receptors as well as cytokine receptors. Participates in signaling pathways that control a diverse spectrum of biological activities including gene transcription, immune response, cell adhesion, cell cycle progression, apoptosis, migration, and transformation. Due to functional redundancy between members of the SRC kinase family, identification of the specific role of each SRC kinase is very difficult. SRC appears to be one of the primary kinases activated following engagement of receptors and plays a role in the activation of other protein tyrosine kinase (PTK) families. Receptor clustering or dimerization leads to recruitment of SRC to the receptor complexes where it phosphorylates the tyrosine residues within the receptor cytoplasmic domains. Plays an important role in the regulation of cytoskeletal organization through phosphorylation of specific substrates involved in this process. When cells adhere via focal adhesions to the extra-cellular matrix, signals are transmitted by integrins into the cell and result in tyrosine phosphorylation of a number of focal adhesion proteins, including PTK2/FAK1 and paxillin (PXN). Also active at the sites of cell-cell contact adherens junctions and at gap junctions. Implicated in the regulation of pre-mRNA-processing. Might be involved not only in mediating the transduction of mitogenic signals at the level of the plasma membrane but also in controlling progression through the cell cycle via interaction with regulatory proteins in the nucleus.[1] [2] Publication Abstract from PubMedSrc kinase belongs to the family of Src-related nonreceptor tyrosine kinases. Because of its physiological role in cell growth and proliferation, its activity is strictly controlled by several mechanisms. Nevertheless, in viral Src kinase (v-Src) some of these mechanisms fail, and its uncontrolled activity is responsible for the occurrence of cancer. Here, the crystal structures of three SH3-domain mutants of v-Src were determined to unveil the effects of these oncogenic mutations in this regulatory domain. Mutations in the n-Src and distal loops have a low impact on the overall structure of the domain and its capacity to form intertwined dimers. However, mutations in the RT loop compromise the stability of the domain and make the protein very prone to aggregation. Additionally, these mutations prevent the formation of intertwined dimers. The results show a synergistic effect between mutations in the RT loop and those in the n-Src and distal loops. Analysis of the structures of the v-Src SH3-domain mutants and the closed inactive conformation of cellular Src kinase (c-Src) point to a loss of the interactions that are required to establish the compact inactive form of the kinase. Nevertheless, an analysis of structures of the c-Src SH3 domain complexed with class I and II peptides points to minor changes in the interactions between the v-Src SH3 domain and these peptides. In this way, the structures reported here indicate that mutations in the RT loop might impair the kinase regulation mechanism without affecting the recognition of short proline-rich motifs in the target proteins of the kinase, thus explaining the oncogenic behaviour of the protein. The impact of oncogenic mutations of the viral Src kinase on the structure and stability of the SH3 domain.,Salinas-Garcia MC, Plaza-Garrido M, Camara-Artigas A Acta Crystallogr D Struct Biol. 2021 Jun 1;77(Pt 6):854-866. doi:, 10.1107/S2059798321004344. Epub 2021 May 19. PMID:34076598[3] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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