title: Roles of the SH2 and SH3 domains in the regulation of neuronal Src kinase functions.
abstract: Previous studies demonstrated that intra-domain interactions between Src family kinases (SFKs), stabilized by binding of the phosphorylated C-terminus to the SH2 domain and/or binding of the SH2 kinase linker to the SH3 domain, lock the molecules in a closed conformation, disrupt the kinase active site, and inactivate SFKs. Here we report that the up-regulation of N-methyl-D-aspartate receptors (NMDARs) induced by expression of constitutively active neuronal Src (n-Src), in which the C-terminus tyrosine is mutated to phenylalanine (n-Src/Y535F), is significantly reduced by dysfunctions of the SH2 and/or SH3 domains of the protein. Furthermore, we found that dysfunctions of SH2 and/or SH3 domains reduce auto-phosphorylation of the kinase activation loop, depress kinase activity, and decrease NMDAR phosphorylation. The SH2 domain plays a greater regulatory role than the SH3 domain. Our data also show that n-Src binds directly to the C-terminus of the NMDAR NR2A subunit in vitro, with a K(D) of 108.2 ± 13.3 nM. This binding is not Src kinase activity-dependent, and dysfunctions of the SH2 and/or SH3 domains do not significantly affect the binding. These data indicate that the SH2 and SH3 domains may function to promote the catalytic activity of active n-Src, which is important in the regulation of NMDAR functions.
authors.affiliation: Department of Biomedical Sciences, College of Medicine, Florida State University, Tallahassee, FL, USA.
authors.forename: Bradley R
authors.initials: BR
authors.lastname: Groveman
authors.forename: Sheng
authors.initials: S
authors.lastname: Xue
authors.forename: Vedrana
authors.initials: V
authors.lastname: Marin
authors.forename: Jindong
authors.initials: J
authors.lastname: Xu
authors.forename: Mohammad K
authors.initials: MK
authors.lastname: Ali
authors.forename: Ewa A
authors.initials: EA
authors.lastname: Bienkiewicz
authors.forename: Xian-Min
authors.initials: XM
authors.lastname: Yu
mesh_terms: D000818:Animals; D055162:Biocatalysis; D002645:Chickens; D057809:HEK293 Cells; D006801:Humans; D010766:Phosphorylation; D018909:src Homology Domains; D019061:src-Family Kinases / Q000737:chemistry / Q000378:metabolism*
chemical_list: D019061:src-Family Kinases