Uncoupling protein 3 (UCP3) and heart fatty acidbinding protein (HFABP) are pivotal in the regulation of fat metabolism in skeletal muscle cells. Taking binary crossbreed pig of Large White pig and Landrace as control

the expression and localization of UCP3 and HFABP genes and proteins are detected in the skeletal muscle cells by reverse transcription polymerase chain reaction (RTPCR) and histological and immunohistochemistry methods. The results show that both of UCP3 and HFABP are detected in the cytoplasm of muscle cells from Nuogu pig and crossbreed pig. Compared with crossbreed pig

however

the expressions of UCP3 and HFABP in Nuogu pig breed are significantly lower based on the scan results of mean optical density (mOD) of positive pellets in the muscle cells. And the content of serum free fatty acids and intramuscular fat (IMF) of skeletal muscle are much higher in Nuogu pig breeds together with larger muscle cells and intracellular spaces. It sounds that the absorption of fatty acids from blood is less because of the lower HFABP in muscle cells of Nuogu pig. And the production of adenosine triphosphate (ATP) is much more effective in Nuogu pig due to the lower expression of UCP3

which seems to be compensation to the less intake of fatty acids for energy supply in muscle cells of Nuogu pig. As a result

the excessive fatty acids would turn to synthesize triglyceride deposited in fat cells inside of muscle and fat tissue

which results in higher intramuscular fat (IMF) and backfat in Nuogu pig breed. It suggests that both of UCP3 and HFABP genes and the expression in the muscle cells are contributed to the meat quality and backfat traits in Nuogu pig breed.