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J Cell Biol November 1, 2010; 191 (3): 523-35.
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Constitutive recycling of the store-operated Ca2+ channel Orai1 and its internalization during meiosis.

Yu F , Sun L , Machaca K .

The egg''s competency to activate at fertilization and transition to embryogenesis is dependent on its ability to generate a fertilization-specific Ca(2+) transient. To endow the egg with this capacity, Ca(2+) signals remodel during oocyte maturation, including inactivation of the primary Ca(2+) influx pathway store-operated Ca(2+) entry (SOCE). SOCE inactivation is coupled to internalization of the SOCE channel, Orai1. In this study, we show that Orai1 internalizes during meiosis through a caveolin (Cav)- and dynamin-dependent endocytic pathway. Cav binds to Orai1, and we map a Cav consensus-binding site in the Orai1 N terminus, which is required for Orai1 internalization. Furthermore, at rest, Orai1 actively recycles between an endosomal compartment and the cell membrane through a Rho-dependent endocytic pathway. A significant percentage of total Orai1 is intracellular at steady state. Store depletion completely shifts endosomal Orai1 to the cell membrane. These results define vesicular trafficking mechanisms in the oocyte that control Orai1 subcellular localization at steady state, during meiosis, and after store depletion.

PubMed ID: 21041445
PMC ID: PMC3003315
Article link: J Cell Biol
Grant support: [+]

Species referenced: Xenopus laevis
Genes referenced: abcc8 ano1 arf6 cav1 cfp itpr1 orai1 rab11a rab5a rho stim1 tf

Article Images: [+] show captions
References [+] :
Alderton, Evidence for a vesicle-mediated maintenance of store-operated calcium channels in a human embryonic kidney cell line. 2001, Pubmed