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. Author manuscript; available in PMC: 2010 Dec 27.
Published in final edited form as: J Biol Chem. 2007 Nov 15;283(2):1167–1178. doi: 10.1074/jbc.M706218200

Figure 5. Possible subunit arrangement of sGC.

Figure 5

Composite figure depicting possible subunit arrangement of heterodimeric sGC. The structure of the helical putative CC region is not known (labeled ‘?’) as well as the structure of the α1 N-terminal domain. The H-NOX domain is oriented such that helix αF and loop L1 in H-NOX are in proximity to the site that corresponds to where Gsα binds and regulates the homologous adenylyl cyclase (marked ‘X’). In H-NOX, both αF and the N-terminal helical subdomain (αA-αC), which includes the loop L1 containing the potential switch residues D44–D45(14;60), are postulated to shift upon activation (16). To illustrate the N-terminal subdomain shift, we have depicted the superimposed NsH-NOX (red)(16) and TtH-NOX (blue)(14) structures which are postulated to represent the basal and activated state, respectively, of an H-NOX domain. Note that we cannot rule out direct interactions between the H-NOXA domain and the GC catalytic domain, since we do not know the conformation of the intervening sequences and the structure and position of the CC region.