Human β_c associates with 14-3-3ζ, and this association is mediated by the 544-626 region of β_c. HEK 293T cells were either mock-transfected (mock) or transfected with wild-type β_c (wt) or β_c containing C-terminal deletions. Lysates were prepared from transfected cells and either immunoprecipitated with anti–14-3-3ζ antibody (A) or precipitated with either 14-3-3–GST sepharose (B) or GST-sepharose (C). All proteins were separated on 7.5% SDS-PAGE under reducing conditions before Western blotting with anti-β_c antibody (MoAb 1C1).