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Identification of Novel Posttranslational Modifications of Caveolin‐3
Author(s) -
Fuhs Stephen Rush,
Insel Paul A.
Publication year - 2008
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.22.1_supplement.1026.7
Subject(s) - sumo protein , caveolae , caveolin , caveolin 3 , phosphorylation , microbiology and biotechnology , ubiquitin , immunoprecipitation , myristoylation , scaffold protein , caveolin 1 , signal transduction , biology , chemistry , biochemistry , gene
Caveolin, a critical protein component of caveolae, serves as a scaffold for a large number of signaling molecules. This study asks the question: What determines the dynamic nature and extent of localization of signaling components in caveolin/caveolae? Posttranslational modifications (PTMs) influence protein binding and thus we asked if PTMs of caveolin‐3, a muscle‐specific caveolin, help regulate its interactions with signaling proteins. Multiple phosphorylation sites have been identified in caveolins‐1 and ‐2, but not caveolin‐3. To determine whether cav‐3 is phosphorylated, we isolated adult rat cardiac myocytes and immunoprecipitated (IP) with anti‐phosphoamino acid antibodies. Immunoblotting of IPs with anti‐caveolin‐3 antibodies revealed that caveolin‐3 was phosphorylated on Tyr and Thr. In addition, other data has shown that caveolae‐localized signaling components can be regulated by sumoylation (e.g., GLUT4, PTP‐1b and Dynamin). We find that caveolin non‐covalently binds the Small Ubiquitin‐related Modifier (SUMO), implying that caveolin binds sumoylated proteins. Caveolin‐3 co‐immunoprecipitates with Ubc9, the E2 conjugating enzyme, and is itself sumoylated in vitro . We speculate that phosphorylation and sumoylation are PTMs that contribute to the ability of caveolin‐3 to regulate signal transduction. (supported by NIH grants).