Репозиторий Университета

Photoreceptor calcium sensor proteins in detergent-resistant membrane rafts are regulated via binding to caveolin-1


  • Vladimirov V.
  • Zernii E.
  • Baksheeva V.
  • Wimberg H.
  • Kazakov A.
  • Tikhomirova N.
  • Nemashkalova E.
  • Mitkevich V.
  • Zamyatnin A.
  • Lipkin V.
  • Philippov P.
  • Permyakov S.
  • Senin I.
  • Koch K.
  • Zinchenko D.
Дата публикации:01.07.2018
Журнал: Cell Calcium
БД: Scopus
Ссылка: Scopus
Индекс цитирования: 5

Аннтотация

© 2018 Elsevier Ltd  Rod cell membranes contain cholesterol-rich detergent-resistant membrane (DRM) rafts, which accumulate visual cascade proteins as well as proteins involved in regulation of phototransduction such as rhodopsin kinase and guanylate cyclases. Caveolin-1 is the major integral component of DRMs, possessing scaffolding and regulatory activities towards various signaling proteins. In this study, photoreceptor Ca 2+ -binding proteins recoverin, NCS1, GCAP1, and GCAP2, belonging to neuronal calcium sensor (NCS) family, were recognized as novel caveolin-1 interacting partners. All four NCS proteins co-fractionate with caveolin-1 in DRMs, isolated from illuminated bovine rod outer segments. According to pull-down assay, surface plasmon resonance spectroscopy and isothermal titration calorimetry data, they are capable of high-affinity binding to either N-terminal fragment of caveolin-1 (1–101), or its short scaffolding domain (81–101) via a novel structural site. In recoverin this site is localized in C-terminal domain in proximity to the third EF-hand motif and composed of aromatic amino acids conserved among NCS proteins. Remarkably, the binding of NCS proteins to caveolin-1 occurs only in the absence of calcium, which is in agreement with higher accessibility of the caveolin-1 binding site in their Ca 2+ -free forms. Consistently, the presence of caveolin-1 produces no effect on regulatory activity of Ca 2+ -saturated recoverin or NCS1 towards rhodopsin kinase, but upregulates GCAP2, which potentiates guanylate cyclase activity being in Ca 2+ -free conformation. In addition, the interaction with caveolin-1 decreases cooperativity and augments affinity of Ca2 + binding to recoverin apparently by facilitating exposure of its myristoyl group. We suggest that at low calcium NCS proteins are compartmentalized in photoreceptor rafts via binding to caveolin-1, which may enhance their activity or ensure their faster responses on Ca 2+ -signals thereby maintaining efficient phototransduction recovery and light adaptation.


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