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.
Section 20.4 Receptor Tyrosine Kinases and Ras. The receptor tyrosine kinases (RTKs) are the second major type of cell-surface receptors that we discuss in detail in this chapter (see Figure 20-3d, right).igand binding leads to activation of the kinase activity of the receptor and autophosphorylation of tyrosine residues in its cytosolic domain (see Figure 20-31). The activated receptor also can phosphorylate other protein substrates.