Amino acids responsible for reduced affinities of vitamin K-dependent propeptides for the carboxylase.
Amino acids responsible for reduced affinities of vitamin K-dependent propeptides for the carboxylase.
复制标题
负责降低维生素 K 依赖性前肽对羧化酶的亲和力的氨基酸。
DOI：
10.1021/bi991544k
复制
发表时间：
1999
期刊：
影响因子：
2.9
通讯作者：
Stafford,DW
中科院分区：
文献类型：
--
作者：
Stanley,TB;Humphries,J;High,KA;Stafford,DW
The binding of the γ-glutamyl carboxylase to its protein substrates is mediated by a conserved 18 amino acid propeptide sequence found in all vitamin K-dependent proteins. We recently found that the apparent affinities of the naturally occurring propeptides for the carboxylase vary over a 100-fold range and that the propeptide of bone Gla protein has severely impaired affinity for the carboxylase [Stanley, T. B., et al. (1999)J. Biol. Chem. 274, 16940−16944 ()]. Here we report a consensus propeptide sequence that binds tighter (Ki= 0.43 nM) to the carboxylase than any known propeptide sequence. Comparing the factor IX propeptide to the propeptides of protein C, bone Gla protein, and prothrombin, the weakest binding propeptides, allowed us to predict which residues might be responsible for these substrates' relatively weak binding to the carboxylase. We then made propeptides with the predicted amino acid changes and determined their binding affinities. The reduced binding affinity of these propeptides relative to that of FIX is due to residues −15 in protein C, −10 and −6 in bone Gla protein, and −9 in prothrombin. A role for the −9 position was not previously recognized but is further shown by our identification of a new, naturally occurring mutation at this position in factor IX which causes a warfarin-sensitive hemophilia B phenotype. In addition, we find that propeptides with mutations found in warfarin-sensitive patients have reduced affinity for the carboxylase, suggesting a physiological relevance of propeptide binding affinity.
