CDNA CLONES OF THE NEURAL CELL-ADHESION MOLECULE (N-CAM) LACKING A MEMBRANE-SPANNING REGION CONSISTENT WITH EVIDENCE FOR MEMBRANE ATTACHMENT VIA A PHOSPHATIDYLINOSITOL INTERMEDIATE
CDNA CLONES OF THE NEURAL CELL-ADHESION MOLECULE (N-CAM) LACKING A MEMBRANE-SPANNING REGION CONSISTENT WITH EVIDENCE FOR MEMBRANE ATTACHMENT VIA A PHOSPHATIDYLINOSITOL INTERMEDIATE
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DOI：
10.1073/pnas.83.24.9822
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发表时间：
1986-12-01
影响因子：
11.1
通讯作者：
CUNNINGHAM, BA
中科院分区：
文献类型：
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作者：
HEMPERLY, JJ;EDELMAN, GM;CUNNINGHAM, BA
在鸡胚脑中，神经细胞粘附分子N-CAM主要表达为两种多肽，大胞内结构域多肽（Id）（Mr= 160，000）和小胞内结构域多肽（sd）（Mr= 130，000）链，它们的胞质结构域不同，由单个基因转录的RNA的选择性剪接产生。有证据表明，有一种Mr= 120，000的次要N-CAM多肽，其大部分氨基末端序列与Id和sd链相似，但缺乏胞质结构域。我们在此报道了cDNA克隆的分离和表征，cDNA克隆N151似乎编码这第三种N-CAM多肽，我们将其命名为ssd（小表面结构域）多肽链。N151的cDNA插入片段由2437个碱基对（bp）组成。DNA杂交和测序表明，前1721 bp与编码Id链的克隆N208的相应序列几乎相同。在相同的阅读框中，<$N151编码<$N208中不存在的25个氨基酸。N151的其余部分由含有AATACA聚腺苷酸化序列的637-bp非编码区和55-bp poly（A）区组成。与N151互补的信使RNA在发育中比与Id和sd链互补的信使RNA出现得晚，并且它们的出现与ssd多肽的出现相关。尽管由N151编码的多肽缺乏限定胞质结构域的膜区域，但它在其羧基末端确实含有一段相对疏水的氨基酸，该氨基酸类似于在通过脂质磷脂酰肌醇附着于膜的膜蛋白前体中所见的氨基酸。我们在这里表明，ssd链的鸡N-CAM可以从脑囊泡释放的磷脂酶C的治疗，这表明它也可能有一个磷脂酰肌醇锚。这些结果定义了两种额外的模式，N-CAM的表达可以被调制：通过RNA剪接在一个新的网站，并通过不同的膜附着所产生的多肽通过脂质中间体。
In embryonic chicken brains, the neural cell adhesion molecule N-CAM is expressed mainly as two polypeptides, the large intracellular-domain polypeptide (Id), (Mr=160,000) and the small intracellular-domain polypeptide (sd) (Mr=130,000) chains, that differ in their cytoplasmic domains and that arise by alternative splicing of RNA transcribed from a single gene. There is evidence for a minor N-CAM polypeptide of Mr=120,000 that is similar to the Id and sd chains for most of its amino-terminal sequence, but which lacks a cytoplasmic domain. We report here the isolation and characterization of a cDNA clone, .lambda.N151, that appears to encode this third N-CAM polypeptide, which we designate the ssd (small surface-domain) polypeptide chain. The cDNA insert of .lambda.N151 consists of 2437 base pairs (bp). DNA hybridization and sequencing indicate that the first 1721 bp are nearly identical to the corresponding sequence of clone .lambda.N208, which encodes the Id chain. Following in the same reading frame, .lambda.N151 encodes 25 amino acids not present in .lambda.N208. The rest of .lambda.N151 consists of a 637-bp noncoding region containing an AATACA polyadenylylation sequence and a 55-bp poly(A) tract. Messenger RNAs complementary to .lambda.N151 appear later in development than those complementary to the Id and sd chains, and their appearance is correlated with the appearance of the ssd polypeptide. Although the polypeptide encoded by .lambda.N151 lacks a membrane region that would define a cytoplasmic domain, it does contain at its carboxyl end a relatively hydrophobic stretch of amino acids similar to those seen in precursors of membrane proteins that are attached to membranes via the lipid phosphatidylinositol. We show here that the ssd chain of chicken N-CAM can be released from brain vesicles by treatment with phospholipase C, suggesting that it too may have a phosphatidylinositol anchor. These results define two additional modes by which N-CAM expression can be modulated: by RNA splicing at a new site and by differential membrane attachment of the resulting polypeptide through a lipid intermediate.