Kutschera W, Zauner W, Wiche G, Propst F
Institute of Biochemistry and Molecular Cell Biology, Vienna Biocenter, University of Vienna, Austria.
Genomics. 1998 May 1;49(3):430-6. doi: 10.1006/geno.1998.5294.
We report the genomic organization of the mouse and rat genes coding for the 2460-amino-acid microtubule-associated protein (MAP) 1B. In addition to seven exons that encode full-length MAP1B, we have identified two alternative exons, exon 3A and the novel exon 3U. We demonstrate that alternative MAP1B transcripts containing either exon 3A or exon 3U are expressed in a variety of mouse and rat tissues at about 1 to 10% of the level of regular transcripts. The alternative transcripts, if translated, would give rise to MAP1B isoforms truncated at the N-terminus. The exon/intron organization underlying the alternative transcripts and the N-terminal amino acid sequence of the putative truncated MAP1B isoforms resemble those of MAP1A, providing further evidence for an evolutionary relationship. The detection of alternative transcripts has implications for the interpretation of conflicting results recently obtained in MAP1B knockout mice.
我们报告了编码2460个氨基酸的微管相关蛋白（MAP）1B的小鼠和大鼠基因的基因组结构。除了七个编码全长MAP1B的外显子外，我们还鉴定出两个可变外显子，即外显子3A和新的外显子3U。我们证明，包含外显子3A或外显子3U的可变MAP1B转录本在多种小鼠和大鼠组织中表达，其水平约为正常转录本的1%至10%。这些可变转录本如果被翻译，将产生在N端截短的MAP1B异构体。可变转录本背后的外显子/内含子结构以及推定的截短MAP1B异构体的N端氨基酸序列与MAP1A相似，为进化关系提供了进一步的证据。可变转录本的检测对最近在MAP1B基因敲除小鼠中获得的相互矛盾的结果的解释具有重要意义。
