Glutathione peroxidase-1 (GPx-1) is a key intracellular antioxidant enzyme that reduces hydrogen peroxide to water, limiting its harmful effects. It plays a critical role in modulating cellular oxidant stress and redox-mediated responses. GPx-1 is a selenocysteine (Sec)-containing enzyme, and its expression is regulated by selenium and the incorporation of Sec during translation. The enzyme is involved in various physiological processes, including growth factor-mediated signal transduction, mitochondrial function, and maintaining thiol redox balance. GPx-1 is also implicated in the development and prevention of diseases such as cancer and cardiovascular disease. The review discusses the molecular mechanisms regulating GPx-1 expression and function, including transcriptional, post-transcriptional, translational, and post-translational regulation. GPx-1's role in cellular processes such as oxidative damage, apoptosis, and inflammation is explored, as well as its involvement in cancer and diseases like diabetes and cardiovascular disease. The review also speculates on potential future therapeutic applications of GPx-1. GPx-1 is found in various cellular compartments, including cytosol, mitochondria, and peroxisomes, and is essential for preventing the harmful accumulation of intracellular hydrogen peroxide. The enzyme's activity is regulated by factors such as selenium, redox state, and signaling pathways. The review highlights the importance of GPx-1 in maintaining cellular redox balance and its potential as a therapeutic target for diseases associated with oxidative stress.Glutathione peroxidase-1 (GPx-1) is a key intracellular antioxidant enzyme that reduces hydrogen peroxide to water, limiting its harmful effects. It plays a critical role in modulating cellular oxidant stress and redox-mediated responses. GPx-1 is a selenocysteine (Sec)-containing enzyme, and its expression is regulated by selenium and the incorporation of Sec during translation. The enzyme is involved in various physiological processes, including growth factor-mediated signal transduction, mitochondrial function, and maintaining thiol redox balance. GPx-1 is also implicated in the development and prevention of diseases such as cancer and cardiovascular disease. The review discusses the molecular mechanisms regulating GPx-1 expression and function, including transcriptional, post-transcriptional, translational, and post-translational regulation. GPx-1's role in cellular processes such as oxidative damage, apoptosis, and inflammation is explored, as well as its involvement in cancer and diseases like diabetes and cardiovascular disease. The review also speculates on potential future therapeutic applications of GPx-1. GPx-1 is found in various cellular compartments, including cytosol, mitochondria, and peroxisomes, and is essential for preventing the harmful accumulation of intracellular hydrogen peroxide. The enzyme's activity is regulated by factors such as selenium, redox state, and signaling pathways. The review highlights the importance of GPx-1 in maintaining cellular redox balance and its potential as a therapeutic target for diseases associated with oxidative stress.