SAP97 Controls the Trafficking and Resensitization of the Beta-1-Adrenergic Receptor through Its PDZ2 and I3 Domains

Mohammed M. Nooh, Anjaparavanda P. Naren, Sung Jin Kim, Yang K. Xiang, Suleiman Bahouth

Research output: Contribution to journalArticle

10 Citations (Scopus)

Abstract

Previous studies have determined that the type-1 PDZ sequence at the extreme carboxy-terminus of the ß1-adrenergic receptor (ß1-AR) binds SAP97 and AKAP79 to organize a scaffold involved in trafficking of the ß1-AR. In this study we focused on characterizing the domains in SAP97 that were involved in recycling and resensitization of the ß1-AR in HEK-293 cells. Using a SAP97 knockdown and rescue strategy, we determined that PDZ-deletion mutants of SAP97 containing PDZ2 rescued the recycling and resensitization of the ß1-AR. Among the three PDZs of SAP97, PDZ2 displayed the highest affinity in binding to the ß1-AR. Expression of isolated PDZ2, but not the other PDZs, inhibited the recycling of the ß1-AR by destabilizing the macromolecular complex involved in trafficking and functional resensitization of the ß1-AR. In addition to its PDZs, SAP97 contains other protein interacting domains, such as the I3 sequence in the SRC homology-3 (SH3) domain, which binds to AKAP79. Deletion of I3 from SAP97 (ΔI3-SAP97) did not affect the binding of SAP97 to the ß1-AR. However, ΔI3-SAP97 could not rescue the recycling of the ß1-AR because it failed to incorporate AKAP79/PKA into the SAP97-ß1-AR complex. Therefore, bipartite binding of SAP97 to the ß1-AR and to AKAP79 is necessary for SAP97-mediated effects on recycling, externalization and functional resensitization of the ß1-AR. These data establish a prominent role for PDZ2 and I3 domains of SAP97 in organizing the ß1-adrenergic receptosome involved in connecting the ß1-AR to trafficking and signaling networks.

Original languageEnglish (US)
Article numbere63379
JournalPloS one
Volume8
Issue number5
DOIs
StatePublished - May 16 2013

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Adrenergic beta-1 Receptors
adrenergic receptors
Adrenergic Receptors
Recycling
recycling
beta-1 adrenergic receptors
Macromolecular Substances
HEK293 Cells
Endosomes

All Science Journal Classification (ASJC) codes

  • Biochemistry, Genetics and Molecular Biology(all)
  • Agricultural and Biological Sciences(all)

Cite this

SAP97 Controls the Trafficking and Resensitization of the Beta-1-Adrenergic Receptor through Its PDZ2 and I3 Domains. / Nooh, Mohammed M.; Naren, Anjaparavanda P.; Kim, Sung Jin; Xiang, Yang K.; Bahouth, Suleiman.

In: PloS one, Vol. 8, No. 5, e63379, 16.05.2013.

Research output: Contribution to journalArticle

Nooh, Mohammed M. ; Naren, Anjaparavanda P. ; Kim, Sung Jin ; Xiang, Yang K. ; Bahouth, Suleiman. / SAP97 Controls the Trafficking and Resensitization of the Beta-1-Adrenergic Receptor through Its PDZ2 and I3 Domains. In: PloS one. 2013 ; Vol. 8, No. 5.
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AU - Xiang, Yang K.

AU - Bahouth, Suleiman

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AB - Previous studies have determined that the type-1 PDZ sequence at the extreme carboxy-terminus of the ß1-adrenergic receptor (ß1-AR) binds SAP97 and AKAP79 to organize a scaffold involved in trafficking of the ß1-AR. In this study we focused on characterizing the domains in SAP97 that were involved in recycling and resensitization of the ß1-AR in HEK-293 cells. Using a SAP97 knockdown and rescue strategy, we determined that PDZ-deletion mutants of SAP97 containing PDZ2 rescued the recycling and resensitization of the ß1-AR. Among the three PDZs of SAP97, PDZ2 displayed the highest affinity in binding to the ß1-AR. Expression of isolated PDZ2, but not the other PDZs, inhibited the recycling of the ß1-AR by destabilizing the macromolecular complex involved in trafficking and functional resensitization of the ß1-AR. In addition to its PDZs, SAP97 contains other protein interacting domains, such as the I3 sequence in the SRC homology-3 (SH3) domain, which binds to AKAP79. Deletion of I3 from SAP97 (ΔI3-SAP97) did not affect the binding of SAP97 to the ß1-AR. However, ΔI3-SAP97 could not rescue the recycling of the ß1-AR because it failed to incorporate AKAP79/PKA into the SAP97-ß1-AR complex. Therefore, bipartite binding of SAP97 to the ß1-AR and to AKAP79 is necessary for SAP97-mediated effects on recycling, externalization and functional resensitization of the ß1-AR. These data establish a prominent role for PDZ2 and I3 domains of SAP97 in organizing the ß1-adrenergic receptosome involved in connecting the ß1-AR to trafficking and signaling networks.

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