Final answer:
Receptor Tyrosine Kinases (RTKs) undergo dimerization and autophosphorylation of tyrosine residues upon binding of a signaling molecule to their extracellular domain, triggering a downstream cellular response.
Step-by-step explanation:
Receptor Tyrosine Kinases (RTKs) are enzymes that span the plasma membrane and play a crucial role in cell communication. When a signaling molecule binds to the extracellular domain of an RTK, it causes the receptor to dimerize or pair up with another RTK. This dimerization triggers the autophosphorylation of tyrosine residues on the intracellular domain of the receptors, leading to a downstream cellular response. The phosphorylation of serine/threonine residues is not directly involved in this process.