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?
-in endosome vesicles-on the outer surface of the plasma membrane-within the cytoplasm of the cell-on the cytoplasmic side of the plasma membrane-within the nucleus of the cell

Answer 1

Answer: within the cytoplasm of the cell

Explanation:

There are four main types of receptors, these are:

G-protein linked Receptors

Enzyme-Linked Receptors

Nuclear Receptors

Ligand-Gated Ion Receptors

Out of these four types; It has become apparent that ligand-gated ion channels (ionotropic receptors) in the neuronal plasma membrane interact via their cytoplasmic domains (i.e within the cytoplasm of the cell) with a multitude of intracellular proteins. Another fact is that, Intracellular receptors are located in the cytoplasm of the cell. Also, Ligand-Gated Ion Receptors is the only Hydrophilic Ligand.

Unlike the G-protein linked Receptors (transmembrane protein (TP)). A transmembrane protein (TP) is a type of integral membrane protein that spans the entirety of the cell membrane. Many transmembrane proteins function as gateways to permit the transport of specific substances across the cell membrane. They frequently undergo significant conformational changes to move a substance through the membrane. They usually highly hydrophobic and aggregate and precipitate in water.

Enzyme-Linked Receptors are transmembrane proteins as well, with their ligand-binding domains on the outer surface of the plasma membrane. They are also hydrophobic in nature.

Nuclear Receptors are nuclear hormone receptors that directly binds  within the nucleus of the cell to regulate the expression of targeted genes.