蛋白酪氨酸磷酸酶（PTPs）是许多疾病的新型药物靶点，包括癌症、自身免疫性疾病和神经系统疾病。然而，它们的催化结构域存在高度的结构相似性，阻碍了选择性药物的开发。我们先前的研究发现了两种无功能化的萜类化合物抑制剂，能选择性地抑制PTP1B而不影响T细胞磷酸酶（TCPTP），这两种磷酸酶具有高度的序列保守性。在本研究中，我们运用分子建模和实验验证来研究这种异常选择性的分子基础。分子动力学（MD）模拟表明，PTP1B和TCPTP共享一个氢键网络，将活性位点连接到远离的一个异构口袋；这个网络稳定催化必需的WPD环的闭合构象，与L-11环以及催化结构域另一侧的相邻α3和α7螺旋相连。萜类化合物与两个近端C-端位点之一──α位点和β位点──结合能破坏异构网络；然而，与α位点的结合只能在PTP1B中形成稳定的复合物。在TCPTP中，两个带电残基使α位点的结合受到不利影响，而更有利于结合于两个蛋白之间保守的β位点。因此，我们的发现表明，微小的氨基酸差异在较差保守的α位点上能实现选择性结合，这种特性在化学改造时可能会被增强，并且更广泛地说明了家族性──但功能上相似──异构位点保守性微小差异如何影响抑制结构的选择性（例如片段结构）。

Protein tyrosine phosphatases (PTPs) are emerging drug targets for many diseases, including cancer, autoimmunity, and neurological disorders. A high degree of structural similarity between their catalytic domains, however, has hindered the development of selective pharmacological agents. Our previous research uncovered two unfunctionalized terpenoid inhibitors that selectively inhibit PTP1B over T-cell PTP (TCPTP), two PTPs with high sequence conservation. Here, we use molecular modeling, with supporting experimental validation, to study the molecular basis of this unusual selectivity. Molecular dynamics (MD) simulations suggest that PTP1B and TCPTP share a h-bond network that connects the active site to a distal allosteric pocket; this network stabilizes the closed conformation of the catalytically essential WPD loop, which it links to the L-11 loop and neighboring α3 and α7 helices on the other side of the catalytic domain. Terpenoid binding to either of two proximal C-terminal sites─an α site and a β site─can disrupt the allosteric network; however, binding to the α site forms a stable complex only in PTP1B. In TCPTP, two charged residues disfavor binding at the α site in favor of binding at the β site, which is conserved between the two proteins. Our findings thus indicate that minor amino acid differences at the poorly conserved α site enable selective binding, a property that might be enhanced with chemical elaboration, and illustrate more broadly how minor differences in the conservation of neighboring─yet functionally similar─allosteric sites can affect the selectivity of inhibitory scaffolds (e.g., fragments).