Subcellular sorting of the G-protein coupled mouse somatostatin receptor 5 by a network of PDZ-domain containing proteins.

PSD-95/discs large/ZO-1 (PDZ) domain proteins integrate many G-protein coupled receptors (GPCRs) into membrane associated signalling complexes. Additional PDZ proteins are involved in intracellular receptor trafficking. We show that three PDZ proteins (SNX27, PIST and NHERF1/3) regulate the mouse somatostatin receptor subtype 5 Whereas the PDZ ligand motif of is not necessary for plasma membrane targeting or internalization, it protects the duanyu1942R5 from postendocytic degradation. Under conditions of lysosomal inhibition, recycling of the duanyu1942R5 to the plasma membrane does not depend on the PDZ ligand. However, recycling of the wild type receptor carrying the PDZ binding motif depends on SNX27 which interacts and colocalizes with the receptor in endosomal compartments. PIST, implicated in lysosomal targeting of some membrane proteins, does not lead to degradation of the Instead, overexpressed PIST retains the duanyu1942R5 at the Golgi. NHERF family members release duanyu1942R5 from retention by PIST, allowing for plasma membrane insertion. Our data suggest that PDZ proteins act sequentially on the GPCR at different stages of its subcellular trafficking.

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