The processing requirements include successful completion of: 1  The application process, which includes a background and polygraph examination, a medical examination, a physical fitness evaluation, and a written examination; 2  24-26 weeks of intensive Academy training.
The cell membrane, being exposed to the outside environment, is an important site of cell-cell communication. As such, a large variety of protein receptors and identification proteins, such as antigens, are present on the surface of the membrane.
Cell recognition proteins allow cells to identify each other and interact. Such proteins are involved in immune response, for example. Membrane enzymes produce a variety of substances essential for cell function. Membrane receptor proteins serve as connection between the cell's internal and external environments.