Fig. 5. The effects of ß1 cytoplasmic domain mutants on the expression of the 9EG7 epitope and cell attachment. (A) To examine the effects on the expression of the 9EG7 epitope, human fibroblasts were transiently transfected with the control receptor or tac chimeras containing the wild-type or mutant ß1 cytoplasmic domains as indicated. The effects of expressing these tac chimeras on the expression of the 9EG7 epitope were determined by two-color flow cytometry. Cells expressing levels of the chimeras between 10³ and 10⁴ fluorescence units were analyzed. The expression of the 9EG7 epitope was calculated relative to the total expression of ß1 integrins at the cell surface, which was determined using mAb K20. Because 9EG7 expression is reduced on cells expressing tac-ß1, the data is presented as % inhibition in 9EG7 expression on cells expressing the tac-ß tail chimeras compared to 9EG7 expression on cells expressing the control receptor. The data represent the mean from three separate experiments ± s.e.m. (B) To examine the effects on cell attachment, human fibroblasts were transiently transfected with the control chimeric receptor, or tac chimeras containing wild-type or mutant ß1 cytoplasmic domains as indicated. To determine the effects of expressing these tac-ß1 chimeras on cell attachment to fibronectin, the levels of chimera expression on attached cells, unattached cells and the starting population of cells (cells prior to attachment) were determined by flow cytometry. The mean fluorescence intensity of attached and unattached cells was compared to the starting population and is expressed as the percent of the starting population. Only cells expressing tac chimeras were analyzed (10¹-10⁴ fluorescence units). The data represent the mean from three separate experiments ± s.e.m.

Return to article