Fu D, Skryabin B V, Brosius J, Robakis N K
Department of Psychiatry, Mount Sinai Medical Center, New York, NY 10029, USA.
DNA Cell Biol. 1995 Jun;14(6):485-92. doi: 10.1089/dna.1995.14.485.
The intron-exon organization for the murine dopamine D3 receptor gene was determined. A novel intron of approximately 1 kb was identified in both rat and mouse D3 receptor genes. This intron (termed intron 4) is situated between coding nucleotides 723 and 724, resulting in a split of former exon 4 (containing nucleotides 527-801) into two separate exons (exon 4 and exon 5). Thus, the coding regions of the D2 and D3 receptor genes contain an identical number of exons (seven exons) and share a very similar gene structure. Reverse transcription-PCR experiments revealed a short form of mouse D3 mRNA (D3Short) that lacks the first 63 nucleotides from exon 6, and results from a splicing event occurring within this exon. However, this mRNA variant was not found in either rat or human brain. No dopamine D3 receptor mRNA variants were found deriving from the alternative splicing of exon 5, although its counterpart, exon 6 in the D2 receptor gene, is spliced out to produce the D2Short mRNA. These data suggest that, although the intron-exon organizations of the D2 and D3 receptor genes are similar, the encoded transcripts may be processed differently.
确定了小鼠多巴胺D3受体基因的内含子-外显子组织。在大鼠和小鼠的D3受体基因中均鉴定出一个约1 kb的新内含子。该内含子（称为内含子4）位于编码核苷酸723和724之间，导致原来的外显子4（包含核苷酸527 - 801）分裂为两个单独的外显子（外显子4和外显子5）。因此，D2和D3受体基因的编码区域包含相同数量的外显子（七个外显子），并具有非常相似的基因结构。逆转录-聚合酶链反应实验揭示了一种小鼠D3 mRNA的短形式（D3Short），它缺少外显子6的前63个核苷酸，这是由该外显子内发生的剪接事件导致的。然而，这种mRNA变体在大鼠或人类大脑中均未发现。尽管D2受体基因中的对应外显子6被剪接出去以产生D2Short mRNA，但未发现源自外显子5可变剪接的多巴胺D3受体mRNA变体。这些数据表明，尽管D2和D3受体基因的内含子-外显子组织相似，但编码的转录本可能以不同方式进行加工。
