Abstract：
Progressive rod-cone degeneration (PRCD) is a photoreceptor outer segment (OS) disc-specific protein essential for maintaining OS structures while contributing to rhodopsin packaging densities and distribution in disc membranes. Previously, we showed PRCD undergoing palmitoylation at the sole cysteine (Cys2), where a mutation linked with retinitis pigmentosa (RP) in humans and dogs demonstrates the importance of palmitoylation for protein stability and trafficking to the OS. We demonstrate a mutation, in the polybasic region (PBR) of PRCD (Arg17Cys) linked with RP where an additional lipidation is observed through acyl-RAC. Immunolocalization of transiently expressed R17C in hRPE1 cells depicts similar characteristics to wild-type PRCD; however, a double mutant lacking endogenous palmitoylation at Cys2Tyr with Arg17Cys is comparable to the C2Y protein as both aggregate, mislocalized to the subcellular compartments within the cytoplasm. Subretinal injection of PRCD mutant constructs followed by electroporation in murine retina exhibit mislocalization in the inner segment. Despite being additionally lipidated and demonstrating strong membrane association, the mutation in the PBR affects protein stability and localization to the OS. Acylation within the PBR alone neither compensates for protein stability nor trafficking, revealing defects in the PBR likely lead to dysregulation of PRCD protein associated with blinding diseases.
摘要：
进行性视锥变性（PRCD）是一种感光体外段（OS）椎间盘特异性蛋白，对于维持OS结构至关重要，同时有助于视紫红质包装密度和在椎间盘膜中的分布。以前,我们显示PRCD在唯一的半胱氨酸（Cys2）进行棕榈酰化，其中与人和狗中的色素性视网膜炎（RP）相关的突变证明了棕榈酰化对蛋白质稳定性和向OS运输的重要性。我们展示了一个突变,在与RP连接的PRCD（Arg17Cys）的多碱性区域（PBR）中，通过酰基-RAC观察到额外的脂化。瞬时表达的R17C在hRPE1细胞中的免疫定位描述了与野生型PRCD相似的特征；然而，在Cys2Tyr与Arg17Cys缺乏内源性棕榈酰化的双突变体与C2Y蛋白作为两种聚集体相当，错误定位到细胞质内的亚细胞区室。视网膜下注射PRCD突变体构建体，然后在鼠视网膜中进行电穿孔，在内段表现出错位。尽管还被脂化并表现出强烈的膜关联，PBR中的突变影响蛋白质的稳定性和OS的定位。仅PBR内的酰化既不能补偿蛋白质稳定性，也不能补偿运输，在PBR中揭示缺陷可能导致与致盲疾病相关的PRCD蛋白失调。
