Conformational changes occurring in N‐ras p21 in response to binding of guanine nucleotide and metal ions probed by proteolysis performed under controlled conditions

FEBS Letters

Grant, Michael L.¹  Grand, Roger J.A.¹ 

[1] Department of Cancer Studies, Clinical Research Block, The Medical School, University of Birmingham, Birmingham B15 2TJ, England

关键词: Gene;    N-ras;    Protein;    p21;    GDP;    Mg2+ binding;   

DOI  :  10.1016/0014-5793(89)80976-7

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

Variations in susceptibility to proteolysis by trypsin and chymotrypsin have been used as indicators of conformational changes taking place in N-ras p21 in response to ligand binding. It has been observed that changes occur in undenatured protein, rendering it more resistant to degradation, in the presence of divalent cations such as Mg²⁺ and Ca²⁺ (suggesting direct binding of metals to the polypeptide) and even more markedly in the presence of GDP and/or Mg²⁺ GD. Monovalent cations (Na⁺ or K⁺) cannot substitute for Mg²⁺ or Ca²⁺. Some capacity to bind guanine nucleotide is also retained by p21 treated with 7 M urea, as evidenced by increased resistance to proteolytic degradation, but the ability to bind divalent cations is irreversibly lost following denaturation. Protein prepared under denaturing conditions from a eukaryotic source, however, never regains the resistance to proteolysis shown by the bacterial p21 indicating irreversible changes in secondary and tertiary structure produced under these conditions.

【 授权许可】

Unknown