Sarcolipin

Where it comes from

Made in

Skeletal muscle (above all in larger mammals) and the atria of the heart

Sent out by

Not secreted

Acts on

• SERCA, which it uncouples so that ATP is burnt without moving calcium

What it does

• Turns the muscle pump into a heater: the basis of non-shivering heat in muscle ¹
• Mice without it cannot stay warm in the cold and gain weight on a high-fat diet ¹
• Rises in dystrophic and failing muscle ²

In medicine

• No medicine acts on it and no human disease has been traced to its gene, so it is on no panel
• It is measured in muscle biopsies in research: the level is abnormally high in Duchenne dystrophy, which is read as part of the calcium handling going wrong there ²

Beyond the body’s own use

• Lowering it is the more advanced idea. Halving the gene restored pump function, eased the muscle and heart disease and extended life in a severe mouse model of Duchenne dystrophy, and a gene-silencing injection did much the same ²
• Raising it is the opposite proposal, for obesity, and rests on mice that cannot keep warm without it and put on more weight on a fat-rich diet ¹
• Both ideas are mouse-only. Nothing is in a trial, there is nothing to obtain, and how much of human heat production runs through muscle rather than brown fat is not settled ¹