[7][8] The primary endogenous agonist of HCA1 is lactic acid (and its conjugate base, lactate).

[9] Lactate was initially found to activate HCA1 on fat cells and thereby to inhibit these cells lipolysis i.e., break-down of their fats into free fatty acids and glycerol.

In the brain, HCA1 acts to dampen neuron excitation and may also function to promote neurogenesis (the production of neurons from neural stem cells) and angiogenesis (the formation of new blood vessels from pre-existing blood vessels).

The functions of HCA1 in non-fat and non-neural tissues have not been fully defined but in many cases appear to involve promoting the survival of cells, including various types of cancer cells.

[12] This article on a gene on human chromosome 12 is a stub.