CONSERVED SEQUENCE ELEMENTS IN K PROMOTERS FROM MICE AND HUMANS - IMPLICATIONS FOR TRANSCRIPTIONAL REGULATION AND REPERTOIRE EXPRESSION

Promoter region sequences of human and mouse Igk-V genes were aligned and found to be conserved for about 200-300 base pairs (bp) within sub groups/families. No promoter similarity was found between IGKV promote rs from different human subgroups. Related mouse Igk-V gene families w ere conserved in the promoter region but no similarity was evident whe n promoters from unrelated Igk-V gene families were compared. Most of the human IC;KV promoter subgroups were shown to have mouse counterpar ts with a similarity region that extended about 150 bp upstream of the translational start codon. All promoters contained an octamer sequenc e element. The consensus octamer/decamer sequence was favored but only seven residues within the octamer element were strictly conserved. Fu rthermore, there was also sequence conservation immediately 3' of the octamer where either an A or a G residue was conserved. In addition, o ther DNA elements were also conserved both within the Igk-V subgroups/ families and between mouse and human promoters fi om related subgroups /families. In several of the subgroups/families an E box of the E2A ty pe was conserved 5' or the octamer and a CCCT element was conserved wi thin the IGKV subgroup II and its related mouse Igk-V families. We con clude from this study that conservation of additional sequence element s besides the octamer is a common feature in Igk-V promoters but that distinct elements are conserved only within a given subgroup/family. T hus, the conservation appears to have operated at the level of functio n rather than at the level of recognition sequence for defined transcr iption factors.