IDENTIFICATION OF THE CELL FATE GENE STALKY IN DICTYOSTELIUM

Using insertional mutagenesis, we have isolated a ''stalky'' mutant in which cells destined to become spores end up as stalk cells. Similar mutants were previously observed after chemical mutagenesis, but the a ffected gene could not be isolated. Our mutant, like the previous ones , is in stkA. Its defect is cell-autonomous and not overcome by overex pressing cAMP-dependent protein kinase. stkA is strongly expressed in the prespore region of aggregates but not in the anterior prestalk zon e. The mutant expresses normal levels of prespore-cell transcripts but fails to produce the spore transcript spiA. stkA encodes a predicted 99 kDa protein (STKA) with two putative C4 zinc fingers, one of which is a GATA-type finger, indicating that it may be a transcription facto r. This conclusion is supported by localization of STKA in the nucleus .