Fig. 6. The absence of cleavage of the integrin 6 subunit on the association with CD151 in transfected K562 cells has no effect. Transfected K562 cells, stably expressing 6A^RGGRß1 (uncleaved 6A), were ¹²⁵I-surface-labeled, lysed in 1% CHAPS and immunoprecipitated with anti-integrin subunit or anti-tetraspanin antibodies. Antibodies used for immunoprecipitation were J8H directed against 6, Sam-1 against 5, TS2/16 against ß1, M38 against CD81 and 5C11 against CD151. Note that 6A^RGGRß1 is coprecipitated with CD151 and to a lesser extent with CD81. The integrin 5ß1 is not coprecipitated with tetraspanins; the typical smear around 150 kDa representing 5 is not detected in the precipitates obtained with antibodies against these molecules.