| Autor: |
Coyle, JH, Borinstein, SC, Woodward, EO, Lebman, DA |
| Zdroj: |
International Immunology; May1998, Vol. 10 Issue 5, p669-678, 10p |
| Abstrakt: |
The maturation of IgM-expressing B cells to IgM-secreting plasma cells is associated with both an increase in μ mRNA and the ratio of secreted to membrane forms of μ mRNA. In contrast, previous studies demonstrated that in vitro the secreted form of α mRNA (αs mRNA) predominates regardless of the stage of B cell differentiation. The present study demonstrates that αs mRNA predominates in both B cells derived from the germinal centers of murine Peyer's patches and in the functional IgA memory population, suggesting that in vitro events accurately represent the generation of a secretory IgA response in vivo. Although the predominant usage of the αs poly(A) site is due to RNA processing, it does not depend on either the αs poly(A) site, the 3′ splice site associated with the exon encoding the membrane exon of IgA (αM) or the αM poly(A) sites. Analysis of the sequence of the intron between the αs terminus and αM (αs-αM intron) demonstrates the existence of several potential regulatory elements. Furthermore, the effects of deletions within the α-αM intron on 3′ terminus usage demonstrate that the predominant usage of the proximal terminus is not strictly dependent on the length of the intron. Together with previous work, these observations support the idea that choice of 3′ terminus for all Ig heavy chain genes is regulated by a similar mechanism, but specific sequences within a heavy chain gene can impinge upon that mechanism. [ABSTRACT FROM PUBLISHER] |
| Databáze: |
Complementary Index |
| Externí odkaz: |
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