The accessibility of cell surface sulfhydryl groups in human peripheral lymphocytes was investigated with 5,5′-dithiobis-(2-nitrobenzoic acid) in the presence and absence of ionophore antibiotics and the monoclonal antibody, OKT-3. Only a few accessible protein thiols have been found on the cells as demonstrated by labeling with a fluorescent non-penetrating thiol-marker, monobromotrimethyl-ammoniobimane and the subsequent gel electrophoretic analysis of the protein pattern. Difference spectrophotometric measurement of thiol-DTNB reaction revealed that ionophores altering the transmembrane potential induced an enhanced cell surface thiol-exposure on the minute time scale. The effect showed a dependence on the external concentration of the cations. The binding of monoclonal antibody, OKT-3, directed against T3 complexes, resulted in a similar, concentration-dependent increase of thiol-accessibility. These data are interpreted as early membrane-effects of ionophores and the specific antibody including changes in the conformational equilibrium or vertical displacements of certain membrane proteins. These events are likely to be coupled to the changes in the transmembrane potential of the lymphocytes.
|Number of pages||8|
|Journal||Biochemical and biophysical research communications|
|Publication status||Published - Nov 14 1986|
ASJC Scopus subject areas
- Molecular Biology
- Cell Biology