Practice question

Among three adenylyl cyclases, ACA encoded by acaA is uniquely required for aggregation signaling. Transcribed from multiple developmental promoters, ACA produces both extracellular cAMP for chemotactic relay and intracellular cAMP for PKA-dependent gene expression. Null acaA cells cannot generate cAMP oscillations, remain unable to aggregate, and fail to express early genes despite starvation. Exogenous pulses can rescue development. ACB encoded by acrA acts later during culmination, while ACG encoded by acgA functions as osmosensor controlling spore dormancy. ACP is not a Dictyostelium cyclase isoform, making ACA definitive aggregation-specific enzyme.