Béranger F, Goud B, Tavitian A, de Gunzburg J
Institut National de la Santé et de la Recherche Médicale, Unité 248, Faculté de Médecine, Paris, France.
Proc Natl Acad Sci U S A. 1991 Mar 1;88(5):1606-10. doi: 10.1073/pnas.88.5.1606.
Ras oncogenes encode 21-kDa GTP-binding proteins that are capable of transforming immortalized cells in culture. Ras proteins are bound to the inner face of the plasma membrane by their C-terminal extremity and are thought to transmit their mitogenic signals via an "effector" domain spanning amino acids 32-42. Two ras-related human genes rap1A and rap1B encode 95% homologous 21-kDa proteins that share with Ras p21 the same effector domain and a similar C-terminal Cys-Ali-Ali-Xaa sequence (where Ali is an aliphatic amino acid; also known as a CAAX sequence). The product of the rap1A gene is identical to that of the Krev-1 cDNA, whose overexpression is capable of reverting the phenotype of Ki-ras-transformed NIH 3T3 cells. Antibodies that do not cross-react with Ras and other Ras-related proteins were obtained by immunizing rabbits with a peptide encompassing residues 121-137 of Rap1 proteins. These antibodies were used to investigate the subcellular localization of Rap1 proteins by indirect immunofluorescence and fractionation techniques. Rap1 proteins were found to be tightly bound to cellular membranes. They did not colocalize with Ras proteins on the plasma membrane and were discovered to be associated with the Golgi complex.
Ras癌基因编码21 kDa的GTP结合蛋白，该蛋白能够在培养中转化永生化细胞。Ras蛋白通过其C末端与质膜内表面结合，并被认为通过跨越氨基酸32 - 42的“效应器”结构域传递其促有丝分裂信号。两个与ras相关的人类基因rap1A和rap1B编码95%同源的21 kDa蛋白，它们与Ras p21共享相同的效应器结构域和相似的C末端Cys - Ali - Ali - Xaa序列（其中Ali是脂肪族氨基酸；也称为CAAX序列）。rap1A基因的产物与Krev - 1 cDNA的产物相同，其过表达能够逆转Ki - ras转化的NIH 3T3细胞的表型。通过用包含Rap1蛋白121 - 137位残基的肽免疫兔子，获得了与Ras和其他Ras相关蛋白无交叉反应的抗体。这些抗体用于通过间接免疫荧光和分级分离技术研究Rap1蛋白的亚细胞定位。发现Rap1蛋白与细胞膜紧密结合。它们在质膜上不与Ras蛋白共定位，并被发现与高尔基体复合体相关。
