Caveolin-1 as a regulator of neuronal calcium sensor proteins in phototransduction systemстатьяТезисы
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Дата последнего поиска статьи во внешних источниках: 22 февраля 2019 г.
Аннотация:Caveolin1 is the major regulatory protein of detergent resistant membranes (DRM), which associating with regulation of signaling activity in different organism systems. Rod cell membranes contain cholesterolrich DRM, which accumulate visual cascade proteins. In this study, photoreceptor Ca2+ binding proteins recoverin, NCS1, GCAP1, and GCAP2, belonging to neuronal calcium sensor (NCS) family, were recognized as novel caveolin1 interacting partners. We demonstrated that all studied proteins coprecipitate with caveolin1 from rod outer segment membranes, and can directly interact with caveolin1. Pulldown assay, surface plasmon resonance spectroscopy and isothermal titration calorimetry data indicate that there is interaction with fulllength caveolin1 Nterminal domain (1101) and caveolin1 scaffolding domain (81101). Interestingly that this interaction occurs only in absence of calcium ions, what is supported by surface localization of caveolin1 interaction site in Ca2+ free NCS proteins state. Caveolin1 increase Ca2+ sensitivity of recoverin, and as a consequence, makes its inhibitory activity to rhodopsinkinase more pronounced, but not interfere with recoverinrhodopsin kinase interaction. Amount of free Ca2+, required for this process, consider caveolin1 influence, become in good agreement with physiological conditions of photoreceptor cell. GCAP2 is upregulated by caveolin1 in Ca2+ free state, which increase guanylate cyclase activity. It seems that there is a common mechanism of interaction between caveolin1 and NCS proteins in Ca2+ free state. For recoverin increasing of Ca2+ sensitivity is due to thestabilization of the open conformation of its second Ca2+ binding domain EF2. Obtained data suggest that at low calcium NCS proteins are compartmentalized in photoreceptor rafts via binding to caveolin1, what enhances their activity or ensures their faster responses on Ca2+ signals. The study was supported by RFBR (grant # 15-04-07963).