KLHL-12 is a substrate specific adapter protein for a Cul3-Ring ligase complex. It is a member of the Kelch β-propeller domain subclass of Cullin-Ring substrate recognition domains. This E3 ubiquitin ligase complex has many activities, including acting as a negative regulator of the Wnt signaling pathway by mediating ubiquitination and subsequent proteolysis of Dvl3/Dsh3. KLHL-12 is also known to mediate the polyubiquitination of the dopamine D4 receptor (D4.2), the ubiquitination of KHSRP, a protein that is involved in IRES translation, and also the ubiquitination of Sec31, which is involved in endoplasmic reticulum-Golgi transport by regulating the size of COPII coats. Earlier studies broadly defined the substrate binding regions for D4.2 and Dvl3/Dsh3 to KLHL-12. We tested several peptides from these regions and succeeded in identifying a short peptide that bound to KLHL-12 with low micromolar affinity. To better understand the sequence specificity of this peptide, we used alanine substitutions to map the important residues and obtained an X-ray structure of this peptide bound to KLHL-12. This structure and our peptide affinity measurements suggest a sequence motif for peptides that bind to the top face of KLHL-12. Understanding this binding site on KLHL-12 may contribute to efforts to find small molecule ligands that can either directly inhibit the degradation of substrate proteins or be used in targeted protein degradation strategies using PROTACs.

中文翻译：

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肽与KLHL-12结合的结构解析，KLHL-12是Cul3-Ring E3连接酶复合物中的底物特异性衔接蛋白。

KLHL-12是Cul3-Ring连接酶复合物的底物特异性衔接蛋白。它是Cullin-Ring底物识别结构域的Kelchβ-螺旋桨结构域亚类的成员。这种E3泛素连接酶复合物具有许多活性，包括通过介导泛素化和随后Dvl3 / Dsh3的蛋白水解而充当Wnt信号通路的负调节剂。KLHL-12还可以介导多巴胺D4受体（D4.2）的多泛素化，KHSRP（一种参与IRES翻译的蛋白质）的泛素化，以及Sec31的泛素化，后者与内质网-高尔基体有关通过调节COPII涂层的尺寸进行运输。较早的研究广泛定义了D4.2和Dvl3 / Dsh3与KLHL-12的底物结合区。我们测试了来自这些区域的几种肽，并成功鉴定了以低微摩尔亲和力与KLHL-12结合的短肽。为了更好地理解该肽的序列特异性，我们使用丙氨酸取代来定位重要的残基，并获得了与KLHL-12结合的该肽的X射线结构。这种结构和我们的肽亲和力测量结果表明与KLHL-12顶面结合的肽具有序列基序。了解KLHL-12上的该结合位点可能有助于寻找可以直接抑制底物蛋白质降解或用于PROTAC靶向蛋白质降解策略的小分子配体。我们使用丙氨酸取代来定位重要的残基，并获得了与KLHL-12结合的该肽的X射线结构。这种结构和我们的肽亲和力测量结果表明与KLHL-12顶面结合的肽具有序列基序。了解KLHL-12上的该结合位点可能有助于寻找可以直接抑制底物蛋白质降解或用于PROTAC靶向蛋白质降解策略的小分子配体。我们使用丙氨酸取代来定位重要的残基，并获得了与KLHL-12结合的该肽的X射线结构。这种结构和我们的肽亲和力测量结果表明与KLHL-12顶面结合的肽具有序列基序。了解KLHL-12上的该结合位点可能有助于寻找可以直接抑制底物蛋白质降解或用于PROTAC靶向蛋白质降解策略的小分子配体。