PHYSICOCHEMICAL BASIS OF THE FIVE BASIC SENSES: MOLECULAR MECHANISMS OF SENSORY SIGNAL TRANSDUCTION THROUGH G PROTEIN-COUPLED RECEPTORS

Abstract

Sensory perception enables organisms to detect and respond to environmental stimuli through specialized receptor systems. Among the five primary senses—vision, olfaction, taste, hearing, and touch—vision, olfaction, and several components of taste primarily involve ligand-mediated activation of G protein-coupled receptors (GPCRs), whereas hearing and mechanosensory touch depend predominantly on mechanically gated ion channels. This review examines the physicochemical principles underlying these sensory systems, with particular emphasis on the molecular structure and function of GPCRs involved in sensory signal transduction. The structural organization of seven-transmembrane receptors, ligand recognition, receptor activation, and downstream intracellular signaling pathways are discussed in relation to their roles in visual, olfactory, gustatory, and selected mechanosensory processes. The manuscript also explores the molecular basis of pheromone detection, receptor specificity, and selected bioactive molecules associated with sensory perception. In addition, potential applications of GPCR-mediated mechanisms in pharmaceutical development, cosmetics, fragrance chemistry, food and beverage formulation, and insect population management are described. Several mechanistic interpretations presented in this work, including proposed relationships between molecular dipole moment and odor or taste perception, are discussed as hypotheses that warrant further experimental validation. The review aims to integrate structural biology, molecular recognition, and physicochemical concepts to provide a comprehensive perspective on the molecular mechanisms underlying sensory perception.