What is the Difference Between Internal Receptors and Cell Surface Receptors?

The main difference between internal receptors and cell surface receptors lies in their location within the cell and the type of ligands they bind. Here are the key differences:

Internal Receptors:

• Also known as intracellular or cytoplasmic receptors.
• Found inside the cell, in the cytoplasm or nucleus.
• Respond to hydrophobic ligands that can cross the plasma membrane and reach the receptors inside the cell.
• Internal receptors directly bind to DNA and alter transcription.

Cell Surface Receptors:

• Also known as transmembrane receptors.
• Found embedded in the plasma membrane.
• Respond to external ligands that do not need to travel across the plasma membrane.
• Convert an extracellular signal into an intracellular signal through signal transduction.

There are three general categories of cell-surface receptors: ion channel-linked receptors, G-protein-linked receptors, and enzyme-linked receptors. Each cell-surface receptor has three main components: an external ligand-binding domain, a hydrophobic membrane-spanning region, and an intracellular domain inside the cell.

Comparative Table: Internal Receptors vs Cell Surface Receptors

Here is a table summarizing the differences between internal receptors and cell surface receptors:

Internal receptors, also known as intracellular or cytoplasmic receptors, are located in the cytoplasm and bind to hydrophobic ligands that can enter the cell. In contrast, cell surface receptors are found on the cell membrane and bind to external ligands that do not need to travel across the plasma membrane. Both internal and cell surface receptors are involved in signal transduction and can be classified into different subtypes.