Final answer:
Receptor tyrosine kinases (RTKs) activate Ras proteins by triggering their activation and leading to downstream signaling cascades that affect gene activity, cell proliferation, and differentiation.
Step-by-step explanation:
The correct relationship between receptor tyrosine kinases (RTKs) and Ras proteins is that RTKs activate Ras proteins. RTKs are membrane-spanning proteins that bind to signaling ligands, triggering the dimerization of the receptor. This leads to autophosphorylation of tyrosine residues on the intracellular domain of the receptor, which serves as active docking sites for downstream signaling molecules like Ras proteins.
Ras proteins are small G-proteins that act as molecular switches. When activated by RTKs, Ras proteins undergo a conformational change and bind GTP. This activates the Ras protein, allowing it to initiate a signaling cascade, such as the MAP (mitogen-activated protein) kinase cascade. This pathway leads to the phosphorylation of transcription factors and other nuclear proteins, ultimately affecting gene activity and promoting cell proliferation and differentiation.