A mechanism of the HCO3-

(a) Each of the symbols shown on the membrane in the figure is a transport protein. Write down the general class of transport protein each symbol represents (you can write in the symbol legend).(Word file attached below.)

The one with the lighting bolt looks like an Na+/K+-ATPase ion transporter. The one near the chloride ions is likely a chloride-bicarbonate exchanger, whereas the squarish on on the your bottom left is an ordinary potassium channel.

(b) Give a specific name to transport proteins (1) and (2) including the species being transported, for example, Na+-glucose symporter.

(1) Sodium/hydrogen exchanger
(2) Na+/K+-ATPase ion transporter

(c) Next to each transporter, the chemical species being transported are shown and a line is given for each species. However, the direction of the line is not given except for CO2 and HCO3-. Add an arrow to each line to indicate the direction the species is being transported across the membrane.

(1) Hydrogen is being pumped into the cell, sodium is being pumped out because it is an antiporter.
(2) Potassium is moving into the cell, Sodium is moving out.
(3) Chloride ions are being pumped into the cell, bicarbonate are being pumped out.

Check out:

- http://www.biolreprod.org/content/61/2/452.full.pdf
- http://www.joplink.net/prev/200107/6.html