Department of Biology, Northeastern University, Boston, MA 02115, USA.
FEBS J. 2012 Feb;279(3):361-9. doi: 10.1111/j.1742-4658.2011.08437.x. Epub 2011 Dec 22.
The expression of the six types of human Hb subunits over time is currently considered to be regulated mainly by transcription factors that bind to upstream control regions of the gene (the 'extrinsic' component of regulation). Here, we describe how subunit pairing and further assembly to tetramers in the liganded state is influenced by the affinity of subunits for one another (the 'intrinsic' component of regulation). The adult Hb dimers have the strongest subunit interfaces and the embryonic Hbs the weakest, with fetal Hbs being of intermediate strength, corresponding to the temporal order of their expression. These variable subunit binding strengths and the attenuating effects of acetylation contribute to the differences with which these Hb types form functional O(2) -binding tetramers consistent with gene switching.
目前，人们认为人类 Hb 亚基的六种类型随时间的表达主要受到与基因上游控制区结合的转录因子的调节（调节的“外在”成分）。在这里，我们描述了亚基之间的配对以及在配体结合状态下进一步组装成四聚体如何受到亚基彼此亲和力的影响（调节的“内在”成分）。成人 Hb 二聚体具有最强的亚基界面，而胚胎 Hbs 则最弱，胎儿 Hbs 处于中间强度，与它们表达的时间顺序相对应。这些可变的亚基结合强度和乙酰化的衰减作用导致这些 Hb 类型形成与基因转换一致的功能性 O(2)结合四聚体的能力存在差异。
