BH3-only proteins are a subclass of the Bcl-2 family of proteins, which are central regulators of the mitochondrial pathway of apoptosis. They contain a single Bcl-2 homology domain, known as the BH3 domain, which is critical for their pro-apoptotic function. These proteins act as sentinels that respond to cellular stress signals and initiate apoptosis through the activation of other pro-apoptotic members of the Bcl-2 family, such as Bax and Bak.
