Fan L, Gardner P, Chan S J, Steiner D F
Howard Hughes Medical Institute, University of Chicago, Illinois 60637.
Gen Comp Endocrinol. 1993 Jul;91(1):25-30. doi: 10.1006/gcen.1993.1100.
Because hummingbirds exhibit the highest mass-specific metabolic rates seen among vertebrates and rely on sugars as their main energy source, we have investigated the structure of hummingbird insulin (Selaphorus rufus) to determine whether it possesses structural adaptations that increase its receptor binding affinity (potency). We report here the nucleotide sequence of hummingbird proinsulin determined from hummingbird genomic DNA. The predicted amino acid sequence of the A-chain of hummingbird insulin is identical to that of chickens and the B-chain differs by only one amino acid at a noncritical position, B2 (Val in hummingbird and Ala in chicken). These findings suggest that alterations in secretory and metabolic dynamics of insulin are of greater importance than changes in binding affinity in the adaptation to states of high carbohydrate flux in these very energetic organisms.
由于蜂鸟展现出脊椎动物中最高的质量特异性代谢率，且依赖糖类作为主要能量来源，我们研究了蜂鸟（红喉北蜂鸟）胰岛素的结构，以确定其是否具有能提高受体结合亲和力（效力）的结构适应性。我们在此报告从蜂鸟基因组DNA中确定的蜂鸟胰岛素原的核苷酸序列。蜂鸟胰岛素A链的预测氨基酸序列与鸡的相同，B链仅在一个非关键位置B2处有一个氨基酸不同（蜂鸟为缬氨酸，鸡为丙氨酸）。这些发现表明，在这些能量需求极高的生物适应高碳水化合物通量状态的过程中，胰岛素分泌和代谢动力学的改变比结合亲和力的变化更为重要。
