Abstract
In permeabilized human T lymphocytes, phospholipase C (PLC)-mediated metabolism of polyphosphatidylinositols can be stimulated by triggering the Tcell antigen receptor/CD3 antigen complex (Ti/CD3) with the CD3 antibody UCHT1 or by activation of G proteins with the non-hydrolyzable guanine nucleotide analogue, guanosine 5'-0-(3-thiotrisphosphate) (GTP[S]). Ti/CD3 induction of inositol phosphate production demonstrated no dependence on exogenous guanine nucleotides. Furthermore, Ti/CD3 stimulation did not influence the kinetics or dose-response of GTP[S]-induced inositol phosphate production, suggesting that the Ti/CD3 complex does not regulate guanine nucleotide exchange on the G protein pool stimulated by GTP[S]. These data indicate that the Ti/CD3 complex is not G protein-linked to PLC in a manner analogous to the G protein linkage of receptors to adenylate cyclase. However, the inhibitory guanine nucleotide, GDP, antagonizes not only GTP[S]-induced polyphosphatidylinositol hydrolysis but also UCHT1-induced inositol phosphate production. These data infer that a G protein can modulate the coupling of the Ti/CD3 complex to PLC and that there may be some 'cross-talk' between Ti/CD3 and G protein PLC coupling mechanisms.
| Original language | English |
|---|---|
| Pages (from-to) | 2102-2107 |
| Number of pages | 6 |
| Journal | Journal of Immunology |
| Volume | 146 |
| Issue number | 7 |
| Publication status | Published - 1 Apr 1991 |
ASJC Scopus subject areas
- Immunology and Allergy
- Immunology