Baker M D, Wu G E, Toone W M, Murialdo H, Davis A C, Shulman M J
J Immunol. 1986 Sep 1;137(5):1724-8.
In order to define the molecular requirements for IgM pentamer formation, we have isolated several mutant hybridomas which produce predominantly monomeric IgM. For one such mutant, 102, we synthesized a cDNA clone of its mu-mRNA, and found an in-frame 39-bp deletion, which thus encodes a mu-chain lacking amino acids 550-562, a region spanning the fourth constant domain and the tail of the mu-chain. To prove that this deletion is sufficient to block pentamer formation, we used site-directed mutagenesis to construct a mu-gene lacking these 39 bp, and have shown that the expression of this altered mu-gene results in the production of monomeric IgM.
为了确定IgM五聚体形成的分子要求，我们分离了几种主要产生单体IgM的突变杂交瘤。对于其中一个这样的突变体102，我们合成了其μ-mRNA的cDNA克隆，发现了一个读框内39bp的缺失，因此编码的μ链缺少氨基酸550-562，该区域跨越第四个恒定结构域和μ链的尾部。为了证明这种缺失足以阻止五聚体形成，我们使用定点诱变构建了一个缺少这39bp的μ基因，并表明这种改变后的μ基因的表达导致了单体IgM的产生。
