TMEM109 and obesity due to melanocortin 4 receptor deficiency: The same region also harbors two transmembrane protein genes: TMEM109 and TMEM132A. Transmembrane proteins constitute a large family of genes participating in various processes such as male fertility and growth [142] in Chinese indigenous cattle breeds, intramuscular fat content in Nellore breed [83, 143], childhood and adult obesity in humans [144, 145] and in immune response [146].