Molecular cloning and expression of chicken C-terminal Src kinase: lack of stable association with c-Src protein.

Abstract

Cloning and sequencing of chicken C-terminal Src kinase (CSK), a tyrosine kinase that phosphorylates the regulatory C-terminal tyrosine residue present on cytoplasmic tyrosine kinases of the Src family, demonstrated a high degree of interspecies conservation as well as src homology 2 and 3 domains N-terminal to the kinase domain. The lack of autophosphorylation sites distinguishes CSK from other tyrosine kinases. CSK is unique and does not belong to a gene family, suggesting that it may phosphorylate other members of the Src family of tyrosine kinases in addition to c-Src. Since complex formation between c-Src and CSK seemed a likely regulatory step in the control of c-Src kinase activity, such an asoation was investigated by immunoprecipitation and Western blotting as well as intracellular localization studies. Although some portions of CSK were found in a membrane fraction, no complex formation between CSK and c-Src was observed, suggesting that the src homology 2 domain ofCSK does not play a role in the direct interaction of c-Src.

Autophosphorylation of Src and Yes blocks their inactivation by Csk phosphorylation

“…However, evidence from the literature and our own results eliminated this possibility. First, attempts by others (Sabe et al, 1992) and us (data not shown) have failed to detect strong and stable complexes between Csk and Src. Second, Src isolated after pre-incubation with Csk and ATP-Mg remain inactivated (Stover et al, 1994).…”

Csk defines the ability of integrin-mediated cell adhesion and migration in human colon cancer cells: implication for a potential role in cancer metastasis

“…It was also shown that all these cells express multiple members of SFK including Yes, Fyn, Lyn and Lck, although there were no dramatic changes in their expressions among them. The activity status of SFK was then assessed with anti-Src pY418 antibody that can recognize autophosphorylated tyrosines of SFKs (SFK pY418), since SFK autophosphorylation is directly associated with its function (Sabe et al, 1992a, b). HCC2998 cells demonstrated only faint signals for SFK autophosphorylation, while HCT15 and HT29 cells showed substantial phosphorylation on SFKs potentially corresponding to c-Src and c-Yes.…”

“…The phosphorylated C-terminal tyrosine binds intramolecularly to the SH2 domain of SFK, thereby generating an inactive conformation Sabe et al, 1992a). The importance of Csk as a negative regulator for SFK and the absence of functional redundancy have been demonstrated by the observation that Csk knockout mice, which are lethal at prenatal stage, exhibited constitutive activation of multiple SFK members (Imamoto and Soriano, 1993;Nada et al, 1993).…”

Rapid activation of sodium–proton exchange and extracellular signal-regulated protein kinase in fibroblasts by G protein-coupled 5-HT1A receptor involves distinct signalling cascades

“…∆mSos-1, from which the guanine nucleotide exchange domain is deleted, was obtained from Dr. M. Sakaue (Kobe, Japan) [32]. Sos-Pro [33], which contains only the proline-rich carboxyterminal fragment of mSos1, and Csk [34] were from T. van Biesen and R. J. Lefkowitz (Duke University). Dominant negative Grb2 (∆NGrb2), in which the N-terminal SH3 domain is deleted, was from A. M. Pendergast (Duke University) [35].…”