Figure 6.

Analysis of α3β1-CD151 stoichiometry. Metabolically labeled HT1080 cells were lysed in 1% Triton X-100, and lysates were cleared using anti-CD151 5C11-conjugated Sepharose (+) or unconjugated Sepharose (−). Lysates were subsequently immunoprecipitated with the indicated antibodies, and immune complexes were resolved by nonreducing SDS-PAGE before detecting integrin α chains (A), CD81 (B), or CD151 (C) by autoradiography. The percent reduction in the levels of integrin immunoprecipitated upon CD151 immunodepletion was determined by measuring the amount of ³⁵S-methionine corresponding to the respective proteins in a Betascope 603 Blot Analyzer. At least 400 counts of ³⁵S-methionine were detected in all positive (i.e., nondepleted) lanes during 1 h; and background (< 10%) was subtracted before dividing CD151 depleted/nondepleted counts.