Biased reading frames of pre-existing DH--JH coding joints and preferential nucleotide insertions at VH--DJH signal joints of excision products of immunoglobulin heavy chain gene rearrangements.

摘要: During B cell differentiation immunoglobulin (Ig) DH segments join to JH segments, followed by joining of VH DJH. Although circular excision products DH--JH rearrangements have been characterized, DJH never isolated. We selectively denatured chromosomal DNA mouse splenocytes and enriched spanning the long distance between DH. Subsequent PCR amplifications allowed identification signal joints Sequence analysis indicated that preexisting coding showed a strong bias for reading frame 1, absence 2, which would allow expression truncated mu chain called D protein. When comparing VH--DJH we observed N-nucleotide insertions be abundant at VH--DH joint, but very sparse while both contained N-insertions. These differences in N region suggest differential control D--J V--DJ rearrangements.