The obesity phenotype of humans with rare mutations of the gene for PC1 challenges our understanding of the physiology and molecular biology of energy homeostasis. However, it is clear that loss of endoproteolytic processing by this and other ways emphasizes the key role of POMC products, the melanocortins, in the regulation of human energy balance.

Differences between humans and animal models, sometimes considerable, make human studies indispensible. There are murine mutations which affect convertase function indirectly and cause obesity, but their human equivalents remain to be discovered.

The obesity phenotype of humans with rare mutations of the gene for PC1 challenges our understanding of the physiology and molecular biology of energy homeostasis. However, it is clear that loss of endoproteolytic processing by this and other ways emphasizes the key role of POMC products, the melanocortins, in the regulation of human energy balance.

Differences between humans and animal models, sometimes considerable, make human studies indispensible. There are murine mutations which affect convertase function indirectly and cause obesity, but their human equivalents remain to be discovered.