Three transposed elements in the intron of a human V sub(K) immunoglobulin gene

Two gene segments coding for the variable region of human immunoglobulin light chains of the kappa type (V sub(K) genes) were found to have unusual structures. The two genes which are called A6 and A22 are located in duplicated gene clusters. Their restriction maps are very similar. About 4 kb of the A22 gene region were sequenced. It turned out that the intron contains an insert with the characteristics of a transposed element. The inserted DNA of 1.2 kb length contains imperfect direct and inverted repeats at its ends; at the insertion site a duplication of five nucleotides was found. Within the inserted DNA one copy each of an Alu element and of the simple sequence motif (T-G) sub(17) were identified. Also these two repetitive sequences are themselves flanked by short direct repeats. The major inserted DNA has no significant homology to published human nucleic acid sequences.