Department of Molecular and Cellular Biology, National Jewish Hospital and Research Center, Denver, CO 80206.
Proc Natl Acad Sci U S A. 1984 Apr;81(7):2127-31. doi: 10.1073/pnas.81.7.2127.
It was shown previously by us that cAMP-dependent protein kinase activity in the cellular slime mold Dictyostelium discoideum increased during the early stages of development. Results from other laboratories showed that during the subsequent stage of cell differentiation and positioning, the accumulation of a number of prespore mRNAs and proteins (but not prestalk mRNAs and proteins) was dependent upon cAMP. The present communication describes the cellular distribution of the cAMP-dependent protein kinase at that stage of development. Pseudoplasmodia were disrupted, and prespore cells were separated from prestalk cells by sedimentation through a Percoll gradient. Prespore cells had approximately 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 [(3)H]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 mRNAs and proteins at the stage at which cAMP appears to be required for the cell type-specific syntheses.
先前我们已经证实，在细胞黏菌盘基网柄菌的早期发育阶段，细胞内 cAMP 依赖性蛋白激酶的活性会增加。其他实验室的研究结果表明，在随后的细胞分化和定位阶段，许多前孢子 mRNA 和蛋白质（而不是前柄 mRNA 和蛋白质）的积累依赖于 cAMP。本通讯描述了该发育阶段 cAMP 依赖性蛋白激酶的细胞分布。通过 Percoll 梯度沉降将假变形体打断，并将前孢子细胞与前柄细胞分离。前孢子细胞中的 cAMP 依赖性蛋白激酶的催化亚基和调节亚基的含量分别比前柄细胞高约 4-5 倍。基于 [(3)H]亮氨酸掺入调节亚基，证明了发育过程中 cAMP 依赖性蛋白激酶的增加反映了酶在前孢子和前柄细胞中的从头合成。这一发现与 cAMP 依赖性蛋白激酶在介导 cAMP 对前孢子特异性 mRNA 和蛋白质合成的作用是一致的，因为在这个阶段，cAMP 似乎是细胞类型特异性合成所必需的。
