Unformatted text preview: his create a net negativity
inside the cell, so this pump is electrogenic. the electronegenic property of this pump contribute
to resting potential in some cells. Uniports
ADP ICF Δ conformation
Pi Δ conformation = Na+ Fig. 5-15 = K+ Secondary Active Transport
Ca2+ ATP Na+ H+ sodium calcium exchanger
sodium proton exchanger (exchanger=antiport)
chloride bicarbonate exchanger Cl- K+
Cl- HCO3- ANTIPORTS Na+
K+, 2Cl- 3Na+ ADP
Pi Na+ 15 mM
K+ 150 mM
Cl- 7 mM + this diagram show 7 2nd active transport. in 2nd active transport the energy of
ions moving down its electrochemical gradient power the movement of another
ion/molecule against its gradient.
the numbers in the middle and bottom show the typical sodium, potassium and
chloride concentraion in mammalian cell. typically, there are lower sodium and
higher potassium inside the cell. most cases, this electrochemical gradient is
establish by secondary active transport (mostly through sodium potassium
ATPase). in most cases the ions that will power the secondary active transport is
sodium ions moving into the cell (see upper left and right hand side). the 3
antiport in lower left which move ions across membrane in 2 opposite direction.
the 4 transporters on the right are symport because they move ions across
membrane in the same direction.
-exception: 2 transporters are power differently. the one on the lower left is power
by electrochemical gradient of chloride or bi carbonate. the one on right the
potassium chloride symport is driven by outward driven electrochemical gradient
-for most transporters, transport is power by sodium gradient, established by
sodium potassium ATPase which play central role in powering cell. Na+ 140 mM
K+ 4 m...
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- Spring '09
- Sodium, Secondary Active Transport, Membrane transport protein, Na+/K+-ATPase