Wei K, Eubanks J H, Francis J, Jia Z, Snead O C
Department of Pediatrics, Hospital for Sick Children, Toronto, Ontario, Canada.
Neuroreport. 2001 Mar 26;12(4):833-7. doi: 10.1097/00001756-200103260-00042.
We have identified a novel splice variant of the metabotropic GABA(B) receptor (R) subunit I, designated GABA(B)R1f, from a rat hippocampus cDNA library screen. GABA(B)R1f shares sequence homology with rat GABA(B)R1a, with the exception of an in-frame deletion of exon 4, resulting in a 21 bp deletion in the coding sequence of the N-terminal extracellular domain. In addition, GABA(B)R1f also contains a 93 bp in-frame insertion in a region of the sequence corresponding to the second extracellular loop and the fifth transmembrane domain, similar to that found in rat GABA(B)R1c. While being ubiquitously (but variably) expressed, reverse-transcription polymerase chain reaction analysis revealed the GABA(B)R1f isoform to be most prevalent in peripheral vs central tissues, suggesting a potential role for this novel isoform in either the mediation of inhibitory transmission in these various tissues, or in as yet defined actions unrelated to central synaptic regulatory mechanisms attributable to GABA(B)R.
我们通过对大鼠海马体cDNA文库的筛选，鉴定出了代谢型γ-氨基丁酸B（GABA(B)）受体1（R1）亚基的一种新型剪接变体，命名为GABA(B)R1f。GABA(B)R1f与大鼠GABA(B)R1a具有序列同源性，但第4外显子存在框内缺失，导致N端胞外结构域编码序列缺失21个碱基对。此外，GABA(B)R1f在对应于第二个胞外环和第五个跨膜结构域的序列区域还包含一个93个碱基对的框内插入，这与在大鼠GABA(B)R1c中发现的情况类似。虽然GABA(B)R1f在各处均有（但表达程度不同）表达，但逆转录聚合酶链反应分析显示，该亚型在外周组织与中枢组织中最为普遍，这表明这种新型亚型可能在这些不同组织的抑制性传递介导过程中发挥作用，或者在与GABA(B)R相关的中枢突触调节机制无关的尚未明确的作用中发挥作用。
