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- AlzhanovaEricsson, AT, et al.
(författare)
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A protein of the SR family of splicing factors binds extensively to exonic Balbiani ring pre-mRNA and accompanies the RNA from the gene to the nuclear pore
- 1996
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Ingår i: Genes & development. - : Cold Spring Harbor Laboratory. - 0890-9369 .- 1549-5477. ; 10:22, s. 2881-2893
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Tidskriftsartikel (refereegranskat)abstract
- We report on the molecular cloning and intracellular localization of a heterogeneous nuclear ribonucleoprotein (hnRNP), Ct-hrp45, one of the major components of pre-mRNP particles in Chironomus tentans. It is shown that hrp45 belongs to the SR family of splicing factors and exhibits high sequence similarity to Drosophila SRp55/B52 and human SF2/ASF. The distribution of hrp45 within the C. tentans salivary gland cells is studied by immunocytology. The hrp45 protein is found to be abundant in the nucleus, whereas it is undetectable in the cytoplasm. The fate of hrp45 in specific pre-mRNP particles, the Balbiani ring (BR) granules, is revealed by immunoelectron microscopy. It is observed that hrp45 is associated with the growing BR pre-mRNP particles and is being added continuously concomitant with the growth of the transcript, indicating that hrp45 is bound extensively to exon 4, which comprises 80-90% of the primary transcript. Furthermore, hrp45 remains bound to the BR RNP particles in the nucleoplasm and is not released until the particles translocate through the nuclear pore. Thus, hrp45 behaves as an hnRNP protein linked to exon RNA (and perhaps also to the introns) rather than as a spliceosome component connected to the assembly and disassembly of spliceosomes. It seems that hrp45, and possibly also other SR family proteins, is playing an important role in the structural organization of pre-mRNP particles and is perhaps participating not only in splicing but also in other intranuclear events.
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| 3. |
- Brandsten, C, et al.
(författare)
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Expression of collagen alpha1(I) mRNA variants during tooth and bone formation in the rat
- 1999
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Ingår i: Journal of dental research. - : SAGE Publications. - 0022-0345 .- 1544-0591. ; 78:1, s. 11-19
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Tidskriftsartikel (refereegranskat)abstract
- Collagen al(I) mRNA is composed of two variants of 5 and 6 kb, differing in the length of the 3' untranslated region. In this work, the nucleotide sequences of the two rat mRNA variants were compared, and their expression pattern in cells forming bone, dentin, and cementum were analyzed. The sequences were determined from cDNA inserts of tooth and bone libraries plus directly from PCR fragments, obtained from bone. A total of 5721 bases of the rat collagen α1(I) sequence from cDNA of tooth and bone was determined. All sequences of the short variant were represented in the long variant. Only the alternatively poly-A additions gave rise to the variants in hard tissue. Two oligonucleotides were chosen as probes, one of which recognized, on Northern blots, the two bands of 5 and 6 kb, and the other the 6-kb variant only. The oligonucleotides were used in in situ hybridization experiments, for study of the distribution of the variants in different extracellular matrix-forming cells. Osteoblasts, odontoblasts, and cementum-associated cells were closely examined in sections from rat maxillae from 2 to 25 days of age. A similar or identical pattern of mRNA expression was observed with both oligonucleotides, indicating that the two mRNA variants were co-expressed in all cases.
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