Peleg S, Schrader W T, O'Malley B W
Department of Cell Biology, Baylor College of Medicine, Houston, Texas 77030.
Biochemistry. 1989 Sep 5;28(18):7373-9. doi: 10.1021/bi00444a034.
DNA binding of chick progesterone receptor B form (PRB) has been examined and compared to that of the A form (PRA). We found that the elution profiles of the two receptors overlap on DNA-cellulose columns. Both PRA or PRB could bind to plasmid DNA equivalently as assayed by sedimentation velocity studies. However, DNA-binding activity of the two receptor forms showed differential sensitivity to reducing agents and to sulfhydryl (SH) reactive reagents. Reducing agents stabilized DNA-binding activity of PRA more efficiently than they stabilized PRB. Moreover, removal of reducing agents from receptor preparations caused preferential loss of DNA binding by PRB compared to the PRA. DNA-binding activity of PRA was readily destroyed by sulfhydryl modifying reagents such as N-ethylmaleimide and iodoacetamide while PRB was 3-4 times less sensitive to these reagents. We conclude the DNA-binding activity of PRB is less stable due to altered accessibility of SH groups despite the amino acid sequence identity of the DNA-binding domains of PRA and PRB.
已对鸡孕酮受体B型（PRB）的DNA结合进行了检测，并与A型（PRA）进行了比较。我们发现这两种受体在DNA纤维素柱上的洗脱曲线重叠。通过沉降速度研究测定，PRA和PRB均可等效地结合质粒DNA。然而，两种受体形式的DNA结合活性对还原剂和巯基（SH）反应性试剂表现出不同的敏感性。还原剂稳定PRA的DNA结合活性比稳定PRB更有效。此外，从受体制剂中去除还原剂会导致PRB比PRA优先丧失DNA结合能力。PRA的DNA结合活性很容易被巯基修饰试剂如N-乙基马来酰亚胺和碘乙酰胺破坏，而PRB对这些试剂的敏感性则低3-4倍。我们得出结论，尽管PRA和PRB的DNA结合结构域氨基酸序列相同，但由于SH基团的可及性改变，PRB的DNA结合活性稳定性较差。
