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Carrier proteins and channel proteins facilitate
diffusion by different mechanism
• Two classes of proteins involved facilitate diffusion
– Carrier Proteins (transporters or permeases )
• bind to the solute molecules
• with change in the conformation of the protein
• move the polar or charged molecules in or out of the cell
through the hydrophobic membrane
– Channel Proteins
•
•
•
•
form hydrophilic channel through the membrane
without any change in the conformation of the protein
molecular weight-up to 600 Da
ion channel
– The transport rate: channel protein > carrier protein