Heme keeps you alive—but too much of it can become a biochemical poison. Your cells therefore need an incredibly precise system to monitor heme and shut down production before things go wrong.
Scientists have now uncovered the molecular “sensor” behind this feedback system. The key is POLDIP2, a mitochondrial protein that was previously associated with DNA-related functions. Researchers discovered that, inside mitochondria, POLDIP2 takes on a completely different role: it uses heme as a molecular glue to connect with ALAS2 and trigger its destruction by the CLPXP protease.
Even more fascinating, this mechanism physically redirects the protease from helping ALAS2 function to dismantling it.
The discovery could help explain—and eventually treat—rare diseases caused by toxic buildup of heme precursors.
🔬 One molecule. One adaptor. One cellular emergency brake.
Citation: Cottle, T., Joh, L., Posner, C., et al. (2026). “An adaptor for feedback regulation of heme biosynthesis by a mitochondrial protease.” Science, 393(6810), eads5397.
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