title: Tyrosine phosphorylation of connexin 43 by v-Src is mediated by SH2 and SH3 domain interactions.
abstract: Reduction of gap junctional communication in v-src transformed cells is accompanied by tyrosine phosphorylation of the gap junction protein, connexin 43 (Cx43). Cx43 is phosphorylated on tyrosine by v-Src. The Src homology 3 (SH3) and Src homology 2 (SH2) domains of v-Src mediate interactions with substrate proteins. SH3 domains interact with proline-rich peptide motifs. SH2 domains associate with short amino acid sequences containing phosphotyrosine. We present evidence that the SH3 and SH2 domains of v-Src bind to proline-rich motifs and a phosphorylated tyrosine residue in the C-terminal tail of Cx43. Cx43 bound to the SH3 domain of v-Src, but not c-Src, in vitro. Tyrosine-phosphorylated Cx43 bound to the SH2 domain of v-Src in vitro. v-Src coprecipitated with Cx43 from v-src-transformed Rat-1 fibroblasts. Mutations in the SH3 and SH2 domains of v-Src, and in the proline-rich region or tyrosine 265 of Cx43, reduced interactions between v-Src and Cx43 in vivo. Tyrosine phosphorylation of Cx43 was dependent on the association of v-Src and Cx43. These results provide further evidence for the direct involvement of v-Src in tyrosine phosphorylation of Cx43 and inhibition of gap junctional communication in v-src-transformed cells.
authors.affiliation: Molecular Biology and Virology Laboratory, The Salk Institute for Biological Studies, La Jolla, California 92037, USA.
authors.forename: M Y
authors.initials: MY
authors.lastname: Kanemitsu
authors.forename: L W
authors.initials: LW
authors.lastname: Loo
authors.forename: S
authors.initials: S
authors.lastname: Simon
authors.forename: A F
authors.initials: AF
authors.lastname: Lau
authors.forename: W
authors.initials: W
authors.lastname: Eckhart
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D002460:Cell Line; D018031:Connexin 43 / Q000737:chemistry / Q000378:metabolism*; D006801:Humans; D008969:Molecular Sequence Data; D015688:Oncogene Protein pp60(v-src) / Q000378:metabolism*; D010766:Phosphorylation; D011233:Precipitin Tests; D011392:Proline / Q000378:metabolism; D051381:Rats; D014443:Tyrosine / Q000378:metabolism*; D018909:src Homology Domains
chemical_list: D018031:Connexin 43; D014443:Tyrosine; D011392:Proline; D015688:Oncogene Protein pp60(v-src)