Final answer:
The proteins that create proton motive force during mitochondrial respiration in mammalian brown fat tissue are uncoupling proteins (UCPs), specifically thermogenin (or UCP1), which allows for the generation of heat instead of ATP production.
Step-by-step explanation:
The type of proteins that create proton motive force during mitochondrial respiration in mammalian brown fat tissue are part of the electron transport chain. These proteins, particularly in brown fat or adipose tissue, contain uncoupling proteins (UCPs) that allow protons (H+) to return to the mitochondrial matrix without the production of ATP, thus generating heat. The presence of UCPs is a specialization of brown fat mitochondria, different from the typical oxidative phosphorylation process where ATP synthase uses the proton gradient to produce ATP.
The key protein in brown adipose tissue that allows for this uncoupling process is known as thermogenin (or UCP1). Thermogenin disrupts the typical creation of ATP by allowing protons to flow back into the mitochondrial matrix, thereby releasing energy as heat - a process vital for thermoregulation in newborns and animals adapted to cold environments.