HMB-PP is then converted further to isopentenyl pyrophosphate (IPP) and dimethylallyl pyrophosphate (DMAPP) by HMB-PP reductase (LytB, IspH).

HMB-PP is an essential metabolite in most pathogenic bacteria including Mycobacterium tuberculosis as well as in malaria parasites, but is absent from the human host.

[3] HMB-PP is the physiological activator ("phosphoantigen") for human Vγ9/Vδ2 T cells, the major γδ T cell population in peripheral blood.

With a bioactivity of 0.1 nM it is 10,000-10,000,000 times more potent than any other natural compound, such as IPP or alkyl amines.

HMB-PP functions in this capacity by binding the B30.2 domain of BTN3A1.