Triazolo[4,5-d]pyrimidin-5-amines were identified from kinase selectivity screening as novel ERK3 inhibitors with sub-100 nanomolar potencies in a biochemical assay using MK5 as substrate and with an attractive kinase selectivity profile. ERK3 crystal structures clarified the inhibitor binding mode in the ATP pocket with impact on A-loop, GC-loop and αC-helix conformations suggesting a potential structural link towards MK5 interaction via the FHIEDE motif. The inhibitors also showed sub-100 nM potencies in a cellular ERK3 NanoBRET assay and with excellent correlation to the biochemical IC₅₀s. This novel series provides valuable tool compounds to further investigate the biological function and activation mechanism of ERK3.

Triazolo[4,5 - d ]pyrimidin-5-amines 从激酶选择性筛选中被鉴定为新型 ERK3 抑制剂，在使用 MK5 作为底物的生化测定中具有低于 100 纳摩尔的效力，并具有有吸引力的激酶选择性特征。ERK3 晶体结构阐明了 ATP 袋中的抑制剂结合模式，对 A 环、GC 环和 αC 螺旋构象的影响表明通过 FHIEDE 基序与 MK5 相互作用存在潜在的结构联系。这些抑制剂还在细胞 ERK3 NanoBRET 测定中显示出低于 100 nM 的效力，并且与生化 IC ₅₀ s具有极好的相关性。这个新系列为进一步研究 ERK3 的生物学功能和激活机制提供了有价值的工具化合物。