Molecular receptors are specialized proteins located on the surface of cells or within them. They play a crucial role in cellular communication by binding to specific molecules, known as ligands, such as hormones, neurotransmitters, or drugs. This binding triggers a response within the cell, leading to various biological effects, such as changes in metabolism or gene expression. These receptors can be classified into different types, including G protein-coupled receptors, ion channel receptors, and nuclear receptors. Each type has a unique structure and function, allowing cells to respond to a wide range of signals from their environment. Understanding molecular receptors is essential for developing targeted therapies in medicine.