1. Specificity: Transport proteins are highly selective and only bind to and transport specific molecules. This specificity is due to the shape and chemical properties of the binding site on the protein, which allows it to interact with its target molecule.
2. Saturation: Transport proteins can become saturated when the concentration of their target molecule is high. This means that there are not enough free binding sites on the protein to bind all of the available molecules. This saturation point limits the rate of transport.
