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bioRxiv · 10.1101/2022.09.15.508083

Cysteine post-translational modifications regulate protein interactions of caveolin-3

Ashford, F.·Brown, E.·Calaghan, S.·Jayasinghe, I.·Henderson, C.·Fuller, W.·Wypijewski, K.
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Abstract

Caveolae are small flask-shaped invaginations of the surface membrane which are proposed to recruit and co-localise signalling molecules. The distinctive caveolar shape is achieved by the oligomeric structural protein caveolin, of which three isoforms exist. Aside from the finding that caveolin-3 is specifically expressed in muscle, functional differences between the caveolin isoforms have not been rigorously investigated. Caveolin-3 is relatively cysteine-rich compared to caveolins 1 and 2, so we investigated its cysteine post-translational modifications. We find that caveolin-3 is palmitoylated at 6 cysteines and becomes glutathiolated following redox stress. We map the caveolin-3 palmitoylation sites to a cluster of cysteines in its C terminal membrane domain, and the glutathiolation site to an N terminal cysteine close to the region of caveolin-3 proposed to engage in protein interactions. Glutathiolation abolishes caveolin-3 interaction with heterotrimeric G protein alpha subunits. Our results indicate that a caveolin-3 oligomer contains up to 66 palmitates, compared to up to 33 for caveolin-1. The additional palmitoylation sites in caveolin-3 therefore provide a mechanistic basis by which caveolae in smooth and striated muscle can possess unique phospholipid and protein cargoes. These unique adaptations of the muscle-specific caveolin isoform have important implications for caveolar assembly and signalling.

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Ashford, F., Brown, E., Calaghan, S., Jayasinghe, I., Henderson, C., Fuller, W., Wypijewski, K.. 2022-09-15. Cysteine post-translational modifications regulate protein interactions of caveolin-3. https://doi.org/10.1101/2022.09.15.508083

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