What are the functions of various types of cellular receptors?

Cellular receptors are crucial components of cell signaling pathways, enabling cells to communicate with each other and respond to external stimuli. There are several types of cellular receptors, each with specific functions:

Ligand-gated Ion Channels:

Ligand-gated ion channels are membrane proteins that open or close in response to the binding of a specific ligand. When the ligand binds to the receptor, the ion channel allows the flow of ions across the cell membrane, altering the cell's electrical potential. This rapid change in ion concentration plays a key role in neuronal signaling and muscle contraction.

G-Protein-Coupled Receptors (GPCRs):

GPCRs are a large family of cell surface receptors that activate intracellular signaling pathways upon ligand binding. When a ligand binds to a GPCR, it triggers the activation of G-proteins, which in turn regulate various downstream signaling cascades. GPCRs are involved in diverse physiological processes, including neurotransmission, hormone signaling, and immune response.

Receptor Tyrosine Kinases (RTKs):

RTKs are cell surface receptors with intrinsic kinase activity, meaning they can phosphorylate tyrosine residues on target proteins. Upon ligand binding, RTKs undergo dimerization and autophosphorylation, initiating signaling cascades that regulate cell growth, proliferation, and differentiation. Aberrant RTK signaling is implicated in various diseases, including cancer.

Overall, cellular receptors are essential for mediating signal transduction and coordinating cellular responses to extracellular cues, highlighting their critical role in maintaining cellular homeostasis.