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. 2019 Mar 28;8:F1000 Faculty Rev-347. [Version 1] doi: 10.12688/f1000research.17358.1

Figure 2. Three-dimensional conformation of the Igκ locus.

Figure 2.

The Igκ locus spans 3.2-Mb topologically associating domain (TAD) and contains about 120 functional Vκ gene segments. ( A) Schematic diagram of the Igκ locus showing the Vs, Js, and C exons and regulatory elements (not to scale). Regulatory elements include intronic Eκ (iEκ), 3′Eκ, Ed, and E88 elements. Contracting element for recombination (Cer) and silencer in the intervening sequence (Sis) are located between the V and J domains and are composed of CTCF-binding elements (CBEs) (purple triangles). The orientation of each CBE is indicated. The Igκ locus is subdivided into five sub-TADs (A–E) as indicated. ( B) Sub-TAD structure of the Igκ locus as determined by Hi-C 2. Each loop represents a sub-TAD that is labeled A–E. The regulatory region containing the Jκ genes, the three distal enhancers, and the constant region are in gray. ( C) Deletion of E88 results in untethering of sub-TADs C and D from the regulatory region.