Intramolecular disulfide bonds of the prolactin receptor short form are required for its inhibitory action on the function of the long form of the receptor.
Intramolecular disulfide bonds of the prolactin receptor short form are required for its inhibitory action on the function of the long form of the receptor.
复制标题
催乳素受体短型的分子内二硫键是其对长型受体功能的抑制作用所必需的。
DOI：
10.1128/mcb.01716-08
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发表时间：
2009
影响因子：
5.3
通讯作者：
Dufau,ML
中科院分区：
文献类型：
--
作者：
Xie,Y-L;Hassan,SA;Qazi,AM;Tsai-Morris,CH;Dufau,ML
催乳素受体（PRLR）的短型（S1 b）通过催乳素受体长型（LF）沉默催乳素诱导的基因转录激活。研究了S1 b胞外亚结构域1（D1）内两个分子内二硫键（S-S）对LF抑制功能的结构和功能贡献。成对半胱氨酸的突变消除了S1 b的抑制作用。突变的S1 b（S1 bx）在细胞表面上的表达不受影响，表明受体的天然样折叠。在S1 b中观察到的组成性JAK 2磷酸化在表达S1 bx的细胞中不存在，并且JAK 2结合被破坏。BRET 50（BRET 50代表达到半最大BRET [生物发光共振能量转移]值所需的受体/供体比的相对亲和力）显示LF/S1 bx异二聚体缔合减少，S1 bx同源二聚体亲和力增加，从而有利于LF同源二聚体和催乳素诱导的信号传导。基于PRLR晶体结构的计算机建模表明，在S-S键断裂后D1的三级结构的微小变化传播到同二聚体的四级结构，影响二聚界面。这些变化解释了S1 bx较高的同源二聚化亲和力，并为其缺乏抑制功能提供了结构基础。通过S-S键稳定的PRLR构象是S1 b对催乳素诱导的LF介导的功能和JAK 2缔合的抑制作用所必需的。
The short form (S1b) of the prolactin receptor (PRLR) silences prolactin-induced activation of gene transcription by the PRLR long form (LF). The functional and structural contributions of two intramolecular disulfide (S-S) bonds within the extracellular subdomain 1 (D1) of S1b to its inhibitory function on the LF were investigated. Mutagenesis of the paired cysteines eliminated the inhibitory action of S1b. The expression of the mutated S1b (S1bx) on the cell surface was not affected, indicating native-like folding of the receptor. The constitutive JAK2 phosphorylation observed in S1b was not present in cells expressing S1bx, and JAK2 association was disrupted. BRET50(BRET50represents the relative affinity as acceptor/donor ratio required to reach half-maximal BRET [bioluminescence resonance energy transfer] values) showed decreased LF/S1bx heterodimeric-association and increased affinity in S1bx homodimerization, thus favoring LF homodimerization and prolactin-induced signaling. Computer modeling based on the PRLR crystal structure showed that minor changes in the tertiary structure of D1 upon S-S bond disruption propagated to the quaternary structure of the homodimer, affecting the dimerization interface. These changes explain the higher homodimerization affinity of S1bx and provide a structural basis for its lack of inhibitory function. The PRLR conformation as stabilized by S-S bonds is required for the inhibitory action of S1b on prolactin-induced LF-mediated function and JAK2 association.