Many receptor tyrosine kinase (RTK) pathways lead to the activation of Ras. To activate Ras, it is necessary to recruit a guanin
e nucleotide exchange factor to the plasma membrane, because Ras is a membrane associated protein. Guanine nucleotide exchange factors, such as SOS, stimulate the exchange of GDP for GTP. However, SOS cannot bind directly to most RTKs. The protein Grb2 has a domain that can bind to phosphorylated tyrosines, and another domain that can bind to SOS. Therefore, Grb2 can bind to active RTKs and recruit SOS to the plasma membrane. Grb2 is an example of what kind of signaling molecule
Grb2 is the best example of adapter protein because it act as connecting molecule. It connects the active/phosphorylated receptor tyrosine kinase (RTKs) to Son of Sevenless (SOS) and generates the bigger signalling complex which plays a critical role in the regulation of signal transduction downwards to the nucleus.
for a celestial body to be a planet of the solar system, it must meet three conditions: it must be in orbit around the Sun, have been molded by its own gravity into a round or nearly round shape, and have “cleared the neighbourhood around its orbit,
