Fig. 8

Schematic representation of slit diaphragm protein endocytosis and recycling pathway. In the Drosophila nephrocyte, plasma membrane invaginates to form lacuna channels (LC). Slit diaphragm (SD) forms at the mouth of these invaginations. The left dashed box indicates the process of slit diaphragm protein endocytosis through the clathrin-mediated endocytosis (CME) pathway. The slit diaphragm proteins at the cell membrane are recognized by the AP-2 complex or other adaptor proteins. Then the AP-2 complex recruits the clathrin complex and like-AP180 (Lap) adaptor to assemble the clathrin coat. Subsequently Shibire (Shi) mediates fission of the endocytic pit from the cell membrane. The clathrin-coated vesicles are later disassembled by auxilin (Aux) and Hsc70-4, releasing AP-2, clathrin and Shi for the next cycle of endocytosis. The uncoated vesicles enter the Rab5-positive early endosome (EE). The slit diaphragm protein cargo is sorted into the Rab11-dependent recycling endosome (RE). Rab11 recruits the exocyst complex to tether the recycling endosome to the cell membrane. The two membranes fuse and the slit diaphragm proteins recycle back to the cell membrane to facilitate assembly of the slit diaphragm structure. The right dashed box indicates slit diaphragm protein endocytosis through the clathrin-independent endocytosis (CIE) pathway, the exact route of which is not clear, which is indicated by the question mark