NO-sensitive guanylyl cyclase: Identification and purification of the dimerization domain

Abstract

The nitric oxide (NO)-sensitive guanylyl cyclase plays a key role in diverse signalling pathways by catalysing the biosynthesis of the messenger molecule cGMP. To date, two isoforms of the enzyme (α1β1 and α2β1) are known, both of which contain a prosthetic heme group bound to the histidine 105 of the β1 subunit. The α1β1 isoform is ubiquitously expressed and is considered to be soluble, whereas the α2β1 isoform is mainly expressed in brain and is located to the membrane via interaction with PSD-95. The three-dimensional structure of NO-sensitive guanylyl cyclase has not been solved. Yet, by sequence comparison the subunits are generally divided into three domains. An N-terminal regulatory domain, a central domain postulated to be involved in dimerization and a C-terminal catalytic domain. For catalytic activity dimerization of the α and β subunit is mandatory, but until recently the regions involved in the interaction were unknown.