Differential cellular distribution of cAMP-dependent protein kinase during development of Dictyostelium discoideum

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Abstract
CAMP-dependent protein kinase activity in the cellular slime mold D. discoideum increased during the early stages of development. During the subsequent stage of cell differentiation and positioning, the accumulation of a number of prespore mRNA and proteins (but not prestalk mRNA and proteins) is dependent on cAMP. The cellular distribution of the cAMP-dependent protein kinase at that stage of development is described. Pseudoplasmodia were disrupted, and prespore cells were separate from prestalk cells by sedimentation through a Percoll gradient. Prespore cells had .apprx. 4-5 times as much of both the catalytic and regulatory subunits of the cAMP-dependent protein kinase as did the prestalk cells. That the increase of cAMP-dependent protein kinase during development reflected de novo synthesis of the enzyme in both prespore and prestalk cells was demonstrated on the basis of [3H]leucine incorporation into the regulatory subunit. The findings are consistent with a role of the cAMP-dependent protein kinase in mediating the effects of cAMP on the synthesis of prespore-specific mRNA and proteins at the stage at which cAMP apparently is required for the cell type-specific syntheses.