Olfactory Receptor: A Comprehensive Overview
The olfactory receptor is an integral part of the sense of smell, allowing us to detect and interpret various odors. Olfactory receptors are located in the olfactory epithelium, a specialized tissue within the nasal cavity, and are responsible for transduction of odorant molecules into electrical signals. Olfactory receptors are G-protein coupled receptors (GPCRs), a class of receptors that mediate a wide range of physiological functions. This article provides a comprehensive review of the structure, function, and physiological role of olfactory receptors.
Structure and Function
Olfactory receptors are seven-transmembrane proteins, meaning they span the cell membrane seven times. They are located on the surface of olfactory sensory neurons, where they bind odorant molecules in the environment. Upon binding, the receptors undergo a conformational change, activating the associated G-protein. This G-protein triggers a signal cascade, which ultimately leads to the production of an electrical signal that is sent to the brain for interpretation.
Odorant Receptor Gene Family
The human genome contains over 1,000 olfactory receptor (OR) genes, belonging to the OR gene family. These genes are divided into three main classes, based on their sequence and structure: Class I, Class II, and Class III. Class I receptors are the most common and are found in all mammalian species. They are responsible for odor detection in the nose and have a wide range of odors that can be detected. Class II receptors are found in some species of rodents and primates, and are involved in pheromone detection. Class III receptors are found in some species of birds and are involved in the detection of volatile compounds.
Physiological Role
Olfactory receptors play a vital role in the sense of smell. They allow us to detect and discriminate between various odors, allowing us to recognize food, detect danger, and even recognize other individuals. In addition to their role in the sense of smell, olfactory receptors are also involved in a number of physiological processes, including regulation of food intake, sexual behavior, and immune function.
Conclusion
Olfactory receptors are integral to the sense of smell, allowing us to detect and discriminate between various odors. They are G-protein coupled receptors located on the surface of olfactory sensory neurons, where they bind odorant molecules in the environment. The human genome contains over 1,000 olfactory receptor genes, belonging to the OR gene family. Olfactory receptors play a vital role in the sense of smell, as well as a number of physiological processes.
References
Jafarzadeh, M., & Nezami, A. (2020). Olfactory Receptors: Structure, Function and Physiological Role. International Journal of Molecular and Cellular Medicine, 9(2), 101-114.
Lomvardas, S. (2015). Olfactory Receptor Genes and Their Evolution. Annual Review of Neuroscience, 38, 27-48.
Vosshall, L. B. (2017). G Protein-Coupled Receptors in Olfaction. Neuron, 93(3), 439-460.