The stimulatory guanine nucleotide-binding protein (G s) is required for hormone-stimulated
cAMP generation. Gnas, the gene encoding the G s α-subunit, is imprinted, and targeted
disruption of this gene in mice leads to distinct phenotypes in heterozygotes depending on
whether the maternal (m−/+) or paternal (+/p−) allele is mutated. Notably, m−/+ mice become
obese, whereas+/p− mice are thinner than normal. In this study we show that despite these
opposite changes in energy metabolism, both m−/+ and+/p− mice have greater sensitivity to …