Interactions with PDZ domain proteins PIST/GOPC and PDZK1 regulate intracellular sorting of the somatostatin receptor subtype 5 |
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Authors: | Wente Wolf Stroh Thomas Beaudet Alain Richter Dietmar Kreienkamp Hans-Jürgen |
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Institution: | Institut für Zellbiochemie und klinische Neurobiologie and Institut für Humangenetik, Universit?tskrankenhaus Hamburg-Eppendorf, Germany. |
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Abstract: | By yeast two-hybrid screening we have identified interaction partners for the intracellular C-terminal tail of the human and rodent somatostatin receptor subtype 5 (SSTR5). Interactions with the PDZ domain-containing proteins PIST and PDZK1 are mediated by the PDZ ligand motif at the C terminus of the receptor; in case of the human and mouse (but not the rat) receptors, a slight sequence variation of this motif also allows for binding of the peroxisomal receptor PEX5. PIST is Golgi-associated and retains SSTR5 in the Golgi apparatus when coexpressed with the receptor; PDZK1 on the other hand associates with the SSTR5 at the plasma membrane. Endogenous SSTR5 in the neuroendocrine AtT-20 tumor cell line is colocalized with PIST in the Golgi apparatus. On a functional level, removal of the PDZ ligand motif of the receptor does not interfere with agonist-dependent internalization of the receptor or its targeting to a Golgi-associated compartment; however, recycling of the receptor to the plasma membrane after washout of the agonist is inhibited, suggesting that the PDZ-mediated interaction of SSTR5 is required for postendocytic sorting. |
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