Colby W W, Hayflick J S, Clark S G, Levinson A D
Mol Cell Biol. 1986 Feb;6(2):730-4. doi: 10.1128/mcb.6.2.730-734.1986.
We expressed six forms of p21-ras polypeptides in Escherichia coli with differing transformation potentials resulting from amino acid substitutions at position 12. The ability of the encoded p21's to autophosphorylate, bind guanine nucleotides, and hydrolyze GTP was assessed. All versions of p21 bound GTP equivalently; the kinase activity, while dependent upon residue 12, did not correlate with the transforming potential of the polypeptide. All transforming versions exhibited an impaired GTPase activity, while a novel nontransforming derivative [p21(pro-12)] possessed an enhanced GTPase activity. These results provide strong support for the proposal that an impairment of the cellular p21 GTPase activity can unmask its transforming potential.
我们在大肠杆菌中表达了六种形式的p21-ras多肽，这些多肽由于第12位氨基酸的替换而具有不同的转化潜能。对编码的p21进行自磷酸化、结合鸟嘌呤核苷酸和水解GTP能力的评估。所有版本的p21等效结合GTP；激酶活性虽依赖于第12位残基，但与多肽的转化潜能无关。所有具有转化能力的版本都表现出GTP酶活性受损，而一种新的无转化能力的衍生物[p21(pro-12)]具有增强的GTP酶活性。这些结果为细胞p21 GTP酶活性受损可揭示其转化潜能这一观点提供了有力支持。
