Belcher S M, Zerillo C A, Levenson R, Ritchie J M, Howe J R
Department of Pharmacology, Yale University School of Medicine, New Haven, CT 06520-8066, USA.
Proc Natl Acad Sci U S A. 1995 Nov 21;92(24):11034-8. doi: 10.1073/pnas.92.24.11034.
Overlapping cDNA clones spanning the entire coding region of a Na-channel alpha subunit were isolated from cultured Schwann cells from rabbits. The coding region predicts a polypeptide (Nas) of 1984 amino acids exhibiting several features characteristic of Na-channel alpha subunits isolated from other tissues. Sequence comparisons showed that the Nas alpha subunit resembles most the family of Na channels isolated from brain (approximately 80% amino acid identity) and is least similar (approximately 55% amino acid identity) to the atypical Na channel expressed in human heart and the partial rat cDNA, NaG. As for the brain II and III isoforms, two variants of Nas exist that appear to arise by alternative splicing. The results of reverse transcriptase-polymerase chain reaction experiments suggest that expression of Nas transcripts is restricted to cells in the peripheral and central nervous systems. Expression was detected in cultured Schwann cells, sciatic nerve, brain, and spinal cord but not in skeletal or cardiac muscle, liver, kidney, or lung.
从兔培养的施万细胞中分离出跨越钠通道α亚基整个编码区的重叠cDNA克隆。该编码区预测一个由1984个氨基酸组成的多肽（Nas），其具有从其他组织分离出的钠通道α亚基的几个特征。序列比较表明，Nasα亚基与从脑中分离出的钠通道家族最为相似（氨基酸同一性约为80%），与在人心脏中表达的非典型钠通道和部分大鼠cDNA即NaG最不相似（氨基酸同一性约为55%）。至于脑II和III亚型，存在两种Nas变体，它们似乎是通过可变剪接产生的。逆转录酶-聚合酶链反应实验结果表明，Nas转录本的表达仅限于外周和中枢神经系统的细胞。在培养的施万细胞、坐骨神经、脑和脊髓中检测到了表达，但在骨骼肌、心肌、肝脏、肾脏或肺中未检测到。
