Identification of a homolog of the Cα3′/hs3enhancer and of an allelic variant of the 3′IgH/hs1,2enhancer downstream the human immunoglobulin α1 gene

摘要

AbstractAlthough four regulatory elements are known downstream the mouse IgH α gene, a single enhancer homologous tohs1,2has been thus far described downstream each human α gene (Chen, C. and Birshtein, B. K.,J. Immunol.1997.159: 1310). We characterized a 10‐kb region downstream the human α1 gene. Two B cell‐specific regulatory elements homologous to the murine Cα3′/hs3andhs1,23′ enhancers were found, which are duplicated downstream α2. Thehs1,2element is in inverted orientation by comparison with a recently reported α1hs1,2element: it appears as a common allelic variant carrying an internal tandem repeat insertion and its prevalence in the human population is 60%. As in the mouse, the humanhs1,2enhancer is flanked with long inverted repeats which may have promoted inversion events through homologous recombination. Although the palindromic organization of the region is maintained in human, sequence identity with rodents focuses on core enhancer elements rather than on flanking repeats. Concerted divergence of both sides of the dyad symmetry suggests that inverted repeats are not just evolutionary remnants but rather play an architectural role in the