Explain Transport proteins in plasma
Transport proteins, embedded in lipid membranes, facilitate the import of nutrients into cells or the release of toxic products into the surrounding medium. Molecules which cannot move across the membrane by diffusion must cross the membrane with the help of transport proteins. As carriers of plasma, these bind to small molecules and ions and transport them throughout the body. Few common examples include:
- An iron-binding protein (transferrin) delivers ferrous ions to hemoglobin synthesizing loci.
- Activity of ions, such as calcium, can be controlled by the ratio of free to bound species.
- When hydrogen ions are bound, proteins act as buffers to minimize the change in pH.
- Since cells are impermeable to proteins, they also participate in determining the distribution of ions and hence electrical potential difference across the cell membrane.
- By virtue of osmotic activity, albumins mediate the distribution of body fluids between plasma and extracelluar compartments