Compartmentalization of bicarbonate-sensitive adenylyl cyclase in distinct signaling microdomains

SPECIFIC AIMSIntracellular targets of the ubiquitous second messenger cAMP are located at great distances from the most widely studied source of cAMP, the G-protein-responsive transmembrane adenylyl cyclases (tmACs). We examined whether the “soluble” adenylyl cyclase (sAC), an alternative source of cAMP in mammalian cells lacking transmembrane spanning domains, was localized near the intracellular targets of cAMP.PRINCIPAL FINDINGS1. sAC is localized to the nucleusTo determine the subcellular distribution of sAC, we generated three affinity-purified polyclonal antisera to distinct, nonoverlapping portions of sAC protein (αN-term, αMiddle, and αC-term) and a panel of monoclonal antibodies to the amino-terminal catalytic domains. The αN-term polyclonal antisera and the panel of monoclonal antibodies recognized full-length sAC protein (187 kDa) (sACfl) and a 50 kDa truncated isoform (sACt) generated by an alternatively spliced transcript, whereas αMiddle and αC-term antibodies recognized only the full-length...