Fig. 4. Cohesin binds multiple sites in the cut regulatory region in Kc cells. Chromatin immunoprecipitation was performed with pre-immune and immune serum for Smc1 and Stromalin, and PCR amplicons spaced 1 kbp apart starting 0.6 kbp upstream of the wing margin enhancer (salmon-colored bar) extending into the transcribed region (blue-green bar) 2.8 kbp downstream of the transcription start site. Enrichment of each amplicon is plotted as the ratio of the amount of PCR product obtained with the immune serum relative to the amount obtained with the pre-immune serum. Most points represent the average of two or three measurements. Enrichment by Smc1 immune serum is plotted in blue, enrichment by Stromalin serum in red, and the black line is the average of the Smc1 and Stromalin values. This reveals cohesin-binding sites at 0.5, 4, 30.5, and 68 kbp upstream of the promoter. These peaks are recognized by an increase in the immune to pre-immune ratio relative to the baseline, which as expected, is close to 1.