Question

You recently identified a molecule that you believe is a primary messenger for a signal transduction mechanism. All you know about this ligand is that it is hydrophilic. Where would you expect to find initial interaction of the molecule with its receptor

Answer 1

Receptor on the outer cell surface.

Step-by-step explanation:

Hydrophilic signal molecules are the water soluble molecules, they are polar polar and therefore cannot pass through the non-polar center of the plasma membrane without any mediator. Water-soluble ligands bind to the extracellular domain of cell surface receptors. Signal molecules cannot enter the cell and thus plasma membrane receptor is required. Plasma membrane receptor form an important class of integral membrane proteins that transmit signals from the extracellular space into the cytoplasm. This group of signal molecules is quite diverse and most are based on amino acids. In some cases the unmodified amino acid is the signal molecule, in others the amino acid is modified into a derivative and in still others amino acids are combined into peptides and proteins.