General Description
This gene encodes a member of the sorting nexin family. Members of this family contain a phox (PX) domain, which is a phosphoinositide binding domain, and are involved in intracellular trafficking. This protein associated with the long isoform of the leptin receptor and with receptor tyrosine kinases for platelet-derived growth factor, insulin, and epidermal growth factor in cell cultures, but its function is unknown. This protein may form oligomeric complexes with family members. (provided by RefSeq)
Biological Activity
Sorting nexin-4 (SNX4) inhibits transferrin receptor (TfnR) endocytosis and colocalizes with transferrin-containing vesicles, thus indicating th at it is a part of the endocytic machinery and involved in endosomal sorting. It associates with key elements of endocytosis like amphiphysin 2 and sequesters it when overexpressed. Through its Phox homology (PX) and Bin-Amphiphysin-Rvs (BAR) domains, SNX4 associates with tubular and vesicular elements. This occurs in a compartment which overlaps with the juxtanuclear endocytic recycling compartment (ERC) and the peripheral early endosomes. It interacts with KIBRA, a protein which binds to dynein light chain 1 and associates with the minus end-directed microtubule motor dynein. SNX4 is involved in driving membrane tubulation, sorting of the TfnR and transport of carriers from early endosomes to the ERC. Thus it has an important role in coordinating sorting along with carrier transport between donor and recipient membranes.
