Efficient transcription of an immunoglobulin kappa promoter requires specific sequence elements overlapping with and downstream of the transcriptional start site.
AUTOR(ES)
Pelletier, M R
RESUMO
The expression of immunoglobulin (Ig) genes depends on tissue-specific elements in the promoter and enhancer regions of light chain and heavy chain genes. In contrast to the complex modular character of Ig enhancers, the promoters appear to be simple, depending primarily on a conserved TATA box and octamer elements. We have analyzed the role of proximal sequences for Igkappa promoter function. Igkappa promoter transcription critically depends on initiator-like sequences and on a downstream element located at +24 to +39 relative to the start site. Replacement of these sequences resulted in strong reduction of promoter activity. In vitro, these elements were found to be more effective in extracts of lymphoid than of non-lymphoid origin. Deletion of the downstream and initiation site regions had a comparable effect on promoter activity to obliteration of the TATA box or octamer element. The downstream sequence was bound by two nuclear proteins, identical to the previously identified Ig-specific C5 and C6 complexes. Whereas C5 is found in HeLa cells and in lymphoid cells, C6 is lymphoid specific. Thus, further specific sequences in addition to the previously characterized elements, the octamer and the TATA box, are required for efficient kappa promoter expression in B lymphocytes.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=147016Documentos Relacionados
- Efficient transcription from the rice tungro bacilliform virus promoter requires elements downstream of the transcription start site.
- Control elements situated downstream of the major transcriptional start site are sufficient for highly efficient polyomavirus late transcription.
- Expression of the psbDII gene in Synechococcus sp. strain PCC 7942 requires sequences downstream of the transcription start site.
- Drosophila retrotransposon promoter includes an essential sequence at the initiation site and requires a downstream sequence for full activity.
- Catabolite repression of the Bacillus subtilis hut operon requires a cis-acting site located downstream of the transcription initiation site.
