The Cip2 and Sty1 proteins associate with each other. (A) Cotranslational assembly and its detection by RIP-chip. Protein B binds to the nascent peptide of protein A. When protein B is immunoprecipitated, it copurifies with protein A and its corresponding polysome. Protein B is identified by its cognate mRNA. (B) Cells expressing Cip2-TAP, Sty1-myc, or both were used for immunoprecipitation experiments with antibodies against protein A. Samples were analysed by Western blotting and probed with peroxidase anti-peroxidase complexes to detect the TAP tag (top panel), or with antibodies against the myc epitope (bottom panel). Equivalent amounts of proteins were loaded for the cell extract (Input) and the supernatant after purification (SN), and the immunoprecipitate (IP) was concentrated at least 5-fold with respect to the original extracts. All samples were run on the same gel. The dotted line indicates where a lane was removed from the image. Note that Sty1-myc is only detected in the IP when Cip2-TAP is coexpressed. (C) As in B, but cells expressed Cip2-GFP, Sty1-myc or both. Cip2-GFP is only detected in the IP when Sty1-myc is coexpressed.