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active transport

I'm starting to revise for exams and am getting really confused!
I understand how carrier proteins work, but can anyone explain how co-transporters work? Thanks

Reply 1

chemicalguy

The sodium-glucose co-transorter is effectively a channel which combines the energy released from ATP hydrolysis to transport a glucose at the same time. as an ion (Na+). So it's used in, say the proximal convoluted tubule of the kidney to reabsorb Na+ and glucose at the same time. One reabsorbed in th eepithelial cells the glucose and Na+ separate and are passedout the other side bt active transport (Na+) or facilitated diffusion (glucose)

Reply 2

Oladz

The co transport protein channel is specific as is the case with many transport protein channels. A molecule can only enter the co-transport channel if it is with the correct type of molecule (hence the co in co-transport).

An example of this is the selective reabsorbtion of glucose in the kidney. Glucose is co transported through the walls of the proximal convoluted tubule with sodium ions.

http://en.wikipedia.org/wiki/Cotransporter

Reply 3

Furuba

There was one book that I read which explained co-transport in terms of something 'minor' - like sodium ions - being transported alongside something 'major' like glucose. In this case, the sodium ions need the glucose molecules to be co-transported from an area of high concentration to an area of low concentration - across a biological membrane. This method of transportation is passive and is naturally faster.