Kobayashi M, Sasaoka T, Takata Y, Ishibashi O, Sugibayashi M, Shigeta Y, Hisatomi A, Nakamura E, Tamaki M, Teraoka H
Third Department of Medicine, Shiga University of Medical Science, Ohtsu, Japan.
Biochem Biophys Res Commun. 1988 Jun 16;153(2):657-63. doi: 10.1016/s0006-291x(88)81145-8.
Failure to cleave the interconnecting site between alpha- and beta-subunit produced insulin proreceptors in the plasma membranes which had markedly low affinity to insulin, leading to extreme insulin resistance in a patient. We performed cDNA sequence analysis of the cleavage site of the insulin proreceptor from the patient. Polymerase chain reaction was used to obtain large amount of cDNA coding for the region including the interconnecting site. A thermostable DNA polymerase, Taq polymerase, successfully produced enough amount of cDNA of the region to be sequenced. The results showed AGG (Arg) to AGT (Ser) point mutation, resulting in the change of interconnecting sequence of the two subunits from -Arg-Lys-Arg-Arg- to -Arg-Lys-Arg-Ser-. These results suggest that the tertial structure change of the cleavage site leads to production of unprocessed insulin proreceptors.
无法切割α亚基和β亚基之间的连接位点会在质膜中产生对胰岛素亲和力极低的胰岛素原受体，导致一名患者出现极度胰岛素抵抗。我们对该患者胰岛素原受体的切割位点进行了cDNA序列分析。采用聚合酶链反应获取大量编码包括连接位点区域的cDNA。一种耐热DNA聚合酶，即Taq聚合酶，成功产生了足够量的待测序区域的cDNA。结果显示存在从AGG（精氨酸）到AGT（丝氨酸）的点突变，导致两个亚基的连接序列从-精氨酸-赖氨酸-精氨酸-精氨酸-变为-精氨酸-赖氨酸-精氨酸-丝氨酸-。这些结果表明切割位点的三级结构变化导致了未加工的胰岛素原受体的产生。
