| Autor: |
Stassen, M. Janna, Bailey, David, Nelson, Stephanie, Chinwalla, Vandana, Harte, Peter J. |
| Zdroj: |
Mechanisms of Development; August 1995, Vol. 52 Issue: 2-3 p209-223, 15p |
| Abstrakt: |
The products of the trithoraxgene are required to stably maintain homeotic gene expression patterns established during embryogenesis by the action of the transiently expressed segmentation genes. We have determined the intron/exon structure of the trxgene and the large alternatively spliced trxRNAs, which are capable of encoding only two protein isoforms. These very large trxproteins differ only in a long Ser- and Gly-rich N-terminal extension, encoded by exon II, which is present only in the larger trxisoform. We have identified a novel variant of the highly conserved nuclear receptor type of DNA binding domain. We have found that the previously identified Cys-rich central region contains multiple novel zinc finger motifs which are also present in the Polycomb-likeprotein and RBP2, a retinoblastoma binding protein. The trxproteins terminate with another novel conserved domain which we have identified in proteins from three kingdoms, including plants and fungi, indicating that has an ancient origin. Many of these proteins are chromosomally associated, suggesting that this domain may be involved in interactions between trxand other highly conserved components of chromatin involved in transcription regulation. The sequence alterations of trxmutations identify the highly conserved regions of trxas critical for the function of these large proteins. We show that zygotically expressed trxRNAs encoding the larger protein isoform are initially expressed in a spatially restricted pattern which overlaps the expression domains of the BX-C genes Ubx, abd-Aand Abd-B. This pattern is transient and evolves into a broader expression domain encompassing the entire germ band during the extended germ band stage. |
| Databáze: |
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