Figure 6. CTCF and cohesin demarcate functional boundaries in and around lymphocyte receptor gene loci.
a) CTCF binding sites limit antisense transcription, accessibility, long-range interactions and premature rearrangement of Igh [18].
b) CTCF and cohesin cooperate to form a boundary at Tcra. A CTCF- and cohesin-binding site with known insulator function is located between Tcra and the neighbouring house keeping gene Dad1. Cohesin deletion results in increased transcription of Dad1, suggesting that cohesin is required for the formation of a boundary that limits Eα enhancer activity to the Tcra locus [17].