A. Thompson et al., IMMUNOGLOBULIN HEAVY-CHAIN GERM-LINE J(H)-C-MU TRANSCRIPTION IN HUMANPRECURSOR B-LYMPHOCYTES INITIATES IN A UNIQUE REGION UPSTREAM OF DQ52, European Journal of Immunology, 25(1), 1995, pp. 257-261
From human precursor B cells which had both immunoglobulin (Ig) heavy
(H) chain loci in germ-line configuration, various IgH chain germ-line
transcripts were isolated and sequenced. These transcripts were shown
to contain sequences derived from the J(H) region, the IgH chain enha
ncer element or the Ig switch region. A number of isolated cDNA clones
contained sequences at their 5' end that were derived from a single e
xon located just upstream of DQ52, designated the mu(o') element. Sequ
ence analysis of a 920-bp genomic DNA segment, containing the mu(o') e
xon and its 5' flanking region, revealed the presence of various conse
rved motifs for DNA-binding proteins, such as E2A, Ets, NF-chi B and A
P-2, which have previously been found in the IgH and L chain enhancers
. We propose that the activity of the mu(o') element, resulting in ger
m-line transcription of the DQ52-J(H) gene segment, is required to gen
erate full accessibility for the V(D)J recombinase.