Ligation of the T-cell Antigen Receptor (TCR) Induces Association of hSos1, ZAP-70, Phospolipase C-γ1, and Other Phosphoproteins with Grb2 and the ζ-Chain of the TCR

Abstract

Signaling by the T-cell antigen receptor (TCR) involves both phospholipase C (PLC)-gamma 1 and p21ras activation. While failing to induce Shc/Grb2 association, ligation of the TCR/CD3 receptor in Jurkat T-cells induced hSos1-Grb2 complexes. In addition to hSos1, Grb2 participates in the formation of a tyrosine phosphoprotein complex that includes 145-, 95-, 70-, 54-, and 36-38-kDa proteins. p145 was identified as PLC-gamma 1 and p70 as the protein tyrosine kinase, ZAP-70. Although of the same molecular weight, p95 was not recognized by an anti-serum to p95 Vav. The SH2 domains of Grb2 and PLC-gamma 1 were required for the formation of this protein complex. In anti-CD3-treated cells, Grb2 redistributed from the cytosol to a particulate cell compartment along with p36/p38, ZAP-70, and PLC-gamma 1. Part of the Grb2 complex associated with the particulate compartment could be extracted with Nonidet P-40, while the rest was Nonidet P-40 insoluble. In both the detergent-soluble and -insoluble fractions, Grb2 coimmunoprecipitated with the zeta-chain of the TCR. Taken together, these results indicate that anti-CD3 induces Grb2-hSos1-PLC-gamma 1-p36/p38-ZAP70 complexes, which localize in the vicinity of TCR-zeta.

Tyrosine phosphorylation of ACK in response to temperature shift‐down, hyperosmotic shock, and epidermal growth factor stimulation

“…However, it has recently been shown that the Grb2/mSos association is also regulated by intracellular signals. For instance, stimula-tion of the EGF receptor [34] or the T cell receptor complex [35,36] increased the association of Grb2 with mSos. The enhancement of the complex formation of ACK with Grb2 following EGF stimulation may be due to a conformational change of the complex upon the binding of Shc to Grb2 (Fig.…”

Hepatocyte Growth Factor-induced Ras Activation Requires ERM Proteins Linked to Both CD44v6 and F-Actin

“…Grb2 is an adaptor protein that mediates signaling from c-Met to Ras via recruiting the guanine nucleotide exchange factor (GEF) Sos (Boguski and McCormick, 1993). The Grb2 complex as it is formed in cells was reconstituted on GST-Grb2 beads in vitro as shown previously (Nel et al, 1995). The specificity of this reconstitution was demonstrated in that the association of c-Met, Gab1, Shp2, and Ras to GST-Grb2 was predominantly observed upon HGF induction in CD44v6-expressing cells ( Figure 2B).…”

Differential Roles of the Src Homology 2 Domains of Phospholipase C-γ1 (PLC-γ1) in Platelet-derived Growth Factor-induced Activation of PLC-γ1 in Intact Cells

“…Furthermore, although PLC-␥1 has been detected in complexes with the CD3 components of the T cell receptor (30), with the T cell-specific nonreceptor PTKs (Lck, Fyn, and ZAP-70) (31)(32)(33), and with LAT (34), the physiological binding targets of the SH2 domains of PLC-␥1 and the PTK responsible for the phosphorylation of PLC-␥1 during T cell activation remain unknown.…”