Fig. 2. Summary of mutations in the ß1 and ß3 cytoplasmic domains. Highly conserved regions of the ß1 and ß3 integrin cytoplasmic domains shown in red were targeted for point mutations. In most cases, the indicated residue (^*) has been changed to alanine. However, other residues have been substituted as indicated. Mutated residues in the ß1 and ß3 tails are shown in blue. All of the ß cytoplasmic domains were expressed in the context of tac chimeras. Also provided is a summary chart of the activity of the different tac-ß tail mutants in the different assays. + to ++++ indicates the degree of similarity of tac-ß tail chimera activity to the wild-type tac-ß chimera in the assay; — indicates that the particular tac-ß tail chimera had no measurable activity in the assay; ND, mutant not tested in the assay; #, data summarized from Mastrangelo et al., 1999b.