{'fraction_non_alphanumeric': 0.03680501174628034, 'fraction_numerical': 0.04541895066562255, 'mean_word_length': 5.085714285714285, 'pattern_counts': {'":': 0, '<': 0, '<?xml version=': 0, '>': 0, 'https://': 0, 'lorem ipsum': 0, 'www.': 0, 'xml': 0}, 'pii_count': 0, 'substrings_counts': 0, 'word_list_counts': {'cursed_substrings.json': 0, 'profanity_word_list.json': 0, 'sexual_word_list.json': 0, 'zh_pornsignals.json': 0}}
Characterizing the Structural Elements Involved in β1‐ Adrenergic Receptor Interaction with SAP97

In this study we characterized the domains in SAP97 that are involved in binding to the β1‐AR and to AKAP79. Among the three PDZs of SAP97, PDZ2 displayed the highest binding affinity to the β1‐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 β1‐AR. However, ΔI3‐SAP97 could not rescue the recycling of the β1‐AR because it failed to incorporate AKAP79 into the SAP97‐ β1‐AR complex. On the other hand, we demonstrated that mutations to alanine at positions 0, −2, and −3 of β1‐AR inhibited recycling of the agonist‐internalized β1‐AR and coimmunoprecipitation of β1‐AR with SAP97 in HEK‐293 cells. Also, we determined that mutating β1‐AR V477 to other small hydrophobic residues (I or L) did not affect recycling of the agonist‐internalized β1‐AR or co‐immunoprecipitation of full β1‐ AR with SAP97. These and other data to be presented define the key elements required for organizing β1‐ adrenergic receptosome involved in connecting the β1‐AR to trafficking and signaling networks.