Phylogenetic analysis of soluble guanylyl cyclases. Inferred phylogeny of the soluble guanylyl cyclase gene family using a Bayesian consensus tree derived from amino acid alignments constructed using MRBAYES 3.0B4 . Posterior probabilities for selected branches are shown at nodes. The receptor guanylyl cyclase orthologues GC-A and GC-B from human and mouse are used as outgroups. The scale bar indicates number of changes per site. C. elegans guanylyl cyclase gene branches are color coded to correspond with chromosomal linkage.