Background During maturation of soluble guanylyl cyclase (sGC), heme insertion into the beta subunit is essential because it enables sGC to recognize nitric oxide (NO) and transduce its biological effects. We used a mammalian cell culture approach and followed heme insertion into both transientlyand endogenously-expressed apo-sGC beta. Although sGC is often associated with heat shock protein 90 (hsp90) in cells, the implications are unclear. Experiments that used pharmacological hsp90 inhibitors, an ATP-ase inactive hsp90 mutant, and heme-dependent or heme-independent sGC activators revealed that heme insertion into apo-sGC requires hsp90 [1].
