CD151 causes substantial modification of integrin complexes. (A) MLECs were labeled with [³H]-palmitate and lysed in 1% Briji-96 buffer. Immunoprecipitations were carried out using mAbs HMβ1-1 + 9EG7 (for β1 integrins) and mAb KMC8 (for CD9). Several integrin-associated proteins, including CD151 itself, are substantially decreased in amount when CD151 is absent (lane 2). These are marked with white arrows and (except for CD151 itself) are labeled as d1-d5. Proteins that are relatively unchanged are marked with black arrows. Note that the integrin β1 subunit does not appear because it does not undergo palmitoylation. Immunoprecipitation of mouse α3 complexes yielded very similar results—proteins similar in size to d1-d5 were again mostly lost from α3β1 complexes when CD151 was absent (not shown). (B) The schematic diagram emphasizes that CD151 plays a key role in linking α3β1 and α6β1 integrins to several other unknown and known proteins, including other tetraspanins CD9 and CD81.