SNX4 (sorting nexin 4) is a phosphatidylinositol 3-phosphate-binding protein that plays critical roles in endosomal recycling and autophagy regulation 1. The protein functions as part of the recycler complex, composed of SNX4, SNX5, and SNX17, which mediates autophagosomal components recycling (ACR) by facilitating the retrieval of autophagosome outer membrane components from autolysosomes 2 3. SNX4 specifically controls the recycling of ATG9A, a lipid scramblase essential for autophagosome membrane expansion, from endolysosomes to early endosomes, thereby sustaining autophagic flux 1. The protein also regulates transferrin receptor recycling and forms complexes with clathrin and dynein to mediate endosome-to-Golgi transport 4 5. In neurons, SNX4 functions as a negative regulator of synaptic vesicle docking and release, affecting synapse ultrastructure by controlling vesicle density at active zones 6. Clinically, SNX4 expression is downregulated in clear cell renal cell carcinoma, correlating with poor prognosis and altered immune infiltration 7. The protein's recycling activities are regulated by mTORC1 through SNX16 phosphorylation and Rab32 family proteins 8 3.