DNase I HS mapping detects 3 major regions in the PU.1 gene.

(A) DNase I HSs detected with probe 1 (P1 in Figure 1B). The arrow indicates a DNase I HS mapping approximately 14-kb upstream of the transcription start site detected in both myeloid 416B cells (left) and T-cell BW5147 cells (right). “0′” indicates no treatment with Dnase I; the triangle above the lanes indicates increasing time of digestion of genomic DNA with DNase I. DNA was digested with EcoRI. (B) DNase I HSs detected with probe 2 (P2 in Figure 1B). The arrows indicate 3 DNase I HSs at 149 bp, 1.4 kb, and 1.8 kb downstream of the transcription start site detected only in myeloid 416B cells (left) but not in T-cell BW5147 cells (right). DNA was digested withEcoRI. (C) DNase I HSs detected with probe 3 (P3 in Figure1B). The arrows indicate DNase I HSs at +9 kb, +12 kb, +15 kb, and +17 kb downstream of the transcription start site. The first 3 are observed only in myeloid 416B cells (left) but not in T-cell BW5147 cells (right); the +17-kb site is observed in both cell types. DNA was digested with BamHI.