A distinct motif for numerous CTCF binding sites in the murine IgH locus

Our studies have revealed that a large class of CTCF binding sites – namely the upstream sites – conform neither to a conformational nor a local recombinase activating role. Their conserved spatial distances upstream of V gene segments suggests a possible role in insulating V gene segments from neighboring V gene segments. In any case, understanding the sequence determinants of CTCF binding to the murine IgH locus should facilitate future studies evaluating how IgH locus accessibility regulates CTCF binding as well as the functions that CTCF plays in regulating the recombinational accessibility of VH gene segments during B cell development. The sequence determinants of CTCF binding to the murine IgH locus in murine primary Rag-deficient and wild type proB cultured in the presence of IL-7.