Endocytic recycling of internalized transmembrane proteins is essential for many important physiological processes. Recent studies have revealed that retromer-related Sorting Nexin family (SNX)–Bin/Amphiphysin/Rvs (BAR) proteins can directly recognize cargoes like cation-independent mannose 6-phosphate receptor (CI-MPR) and Insulin-like growth factor 1 receptor (IGF1R); however, it remains poorly understood how SNX-BARs select specific cargo proteins and whether they recognize additional ligands. Here, we discovered that the binding between SNX-BARs and CI-MPR or IGF1R is mediated by the phox-homology (PX) domain of SNX5 or SNX6 and a bipartite motif, termed SNX-BAR-binding motif (SBM), in the cargoes. Using this motif, we identified over 70 putative SNX-BAR ligands, many of which play critical roles in apoptosis, cell adhesion, signal transduction, or metabolite homeostasis. Remarkably, SNX-BARs could cooperate with both SNX27 and retromer in the recycling of ligands encompassing the SBM, PDZ-binding motif, or both motifs. Overall, our studies establish that SNX-BARs function as a direct cargo-selecting module for a large set of transmembrane proteins transiting the endosome, in addition to their roles in phospholipid recognition and biogenesis of tubular structures.

内化跨膜蛋白的内吞再循环对于许多重要的生理过程至关重要。最近的研究表明，与翻新机相关的分选神经毒素家族（SNX）-Bin /两性纤维蛋白/ Rvs（BAR）蛋白可以直接识别货物，例如不依赖阳离子的甘露糖6-磷酸受体（CI-MPR）和胰岛素样生长因子1受体（IGF1R）；然而，人们对SNX-BARs如何选择特定的货物蛋白以及它们是否识别其他配体的了解仍然很少。在这里，我们发现SNX-BAR与CI-MPR或IGF1R之间的结合是由SNX5或SNX6的pho-同源（PX）域和一个称为SNX-BAR结合基序（SBM）的两部分基序介导的。货物。使用该基序，我们确定了70多个假定的SNX-BAR配体，其中许多在凋亡，细胞粘附，信号转导或代谢物稳态。值得注意的是，SNX-BAR可以与SNX27和Retromer配合使用，以回收包含SBM，PDZ结合基序或两个基序的配体。总体而言，我们的研究表明，SNX-BARs除了可在磷脂识别和管状结构的生物发生中发挥作用外，还可以充当大量通过内体的跨膜蛋白的直接货物选择模块。