UCP3, or Uncoupling Protein 3, is a protein found in the mitochondria of cells, primarily in skeletal muscle and brown adipose tissue. It plays a role in regulating energy metabolism by dissipating the proton gradient generated during cellular respiration, which can lead to heat production instead of ATP synthesis. This protein is part of the uncoupling protein family, which includes other members like UCP1 and UCP2. UCP3 is believed to be involved in fatty acid metabolism and may help protect cells from oxidative stress, contributing to overall metabolic health and energy balance in the body.