Carnero A, Jiménez B
Instituto de Investigaciones Biomédicas, CSIC, Universidad Autónoma de Madrid, Spain.
Biochem Biophys Res Commun. 1995 Nov 22;216(3):748-54. doi: 10.1006/bbrc.1995.2685.
We have analyzed the morphological alterations induced in Xenopus oocytes as a consequence of the microinjection of rap 2A proteins with point mutations at critical positions in the functional domains defined for members of the ras superfamily. Ala 35 rap 2A, a point mutation in the "effector" domain, is able to induce the rearrangement of the pigments in the animal hemisphere termed "mottling". This characteristic phenotype is delayed in asn 17 rap 2A and wild-type rap 2A proteins. A completely different phenotype appears as a consequence of the microinjection of Val 12-rap 2A. This mutant is able to trigger oocyte maturation and is less efficient inducing mottling than Ala 35 or wild-type rap 2A proteins. Neither of these rap 2A mutant proteins is able to counteract ras-induced maturation. However there is a striking interference with progesterone-induced maturation, since wild-type or val 12 rap 2A microinjection reduced the viability of progesterone-treated oocytes. These findings suggest that rap2A proteins are regulatory elements in distinct signal transduction pathways that either lead to the morphological changes associated with the phenotype "mottling" or to oocyte maturation.
我们分析了非洲爪蟾卵母细胞中因显微注射在ras超家族成员功能域关键位置具有点突变的rap 2A蛋白而引起的形态学改变。Ala 35 rap 2A是“效应器”结构域中的一个点突变，能够诱导动物半球色素重排，称为“斑驳化”。这种特征性表型在asn 17 rap 2A和野生型rap 2A蛋白中出现延迟。显微注射Val 12-rap 2A则出现完全不同的表型。这种突变体能够触发卵母细胞成熟，并且在诱导斑驳化方面比Ala 35或野生型rap 2A蛋白效率更低。这些rap 2A突变蛋白均不能抵消ras诱导的成熟。然而，对孕酮诱导的成熟存在显著干扰，因为显微注射野生型或val 12 rap 2A会降低经孕酮处理的卵母细胞的活力。这些发现表明，rap2A蛋白是不同信号转导途径中的调节元件，这些途径要么导致与“斑驳化”表型相关的形态学变化，要么导致卵母细胞成熟。
