OBB Practice Questions - Olimpíada Brasileira De Biologia Exam

Phosphorylation by ATP in the E1 conformation triggers a transition to the E2 conformation, expelling 3 Na+ ions into the extracellular fluid and subsequently importing 2 K+ ions into the cytosol upon dephosphorylation Dephosphorylation of the catalytic alpha-subunit in the cytosolic E2 state facilitates the simultaneous export of 2 Na+ ions down their electrochemical gradient and import of 3 K+ ions against their gradient via passive leakage channels Binding of cytosolic ATP in the open E2 state induces immediate non-covalent opening of a hydrophilic pore that allows 3 Na+ ions and 3 K+ ions to exchange via electroneutral facilitated counter-transport without generating any net charge displacement across the membrane bilayer Phosphorylation by cytosolic GTP drives the continuous mechanical rotation of beta-subunits from an outward-facing E1 state, transporting 2 Na+ ions outward and 1 K+ ion inward with the stoichiometric release of inorganic pyrophosphate into the extracellular fluid