Murphy C S, Steinberg R A
Somat Cell Mol Genet. 1985 Nov;11(6):605-15. doi: 10.1007/BF01534725.
From an S49 mouse lymphoma cell subline that carries an electrophoretic marker mutation in one allele for a regulatory (R) subunit of cyclic AMP-dependent protein kinase, 130 cyclic AMP-resistant mutants were isolated and characterized. Of the 77 independent spontaneous and mutagen-induced isolates identified, 74 had kinases with increased apparent activation constants (KaS) for cyclic AMP-dependent activation. The "Ka" phenotype was invariably correlated with an apparent structural lesion in one R subunit allele. "Charge-shift" lesions in 43 independent isolates were mapped to small regions within the R subunit by two-dimensional gel analysis of partial proteolysis peptides. Nine Ka mutations were distinguished by differences in charge or peptide maps of mutant R subunits, and the mutations were clustered in two regions associated with the cyclic AMP-binding sites of the R subunit. The relative frequencies of different mutations differed among spontaneous, ethyl methanesulfonate-induced, and N-methyl-N'-nitro-N-nitrosoguanidine-induced isolates. Mutation frequencies were also markedly different for the two R subunit alleles; this allele preference was strongest for mutagen-induced lesions in the more carboxy terminal cyclic AMP-binding site.
从一个S49小鼠淋巴瘤细胞亚系中分离并鉴定了130个抗环磷酸腺苷（cAMP）突变体，该亚系在环磷酸腺苷依赖性蛋白激酶的一个调节（R）亚基等位基因中携带电泳标记突变。在鉴定出的77个独立的自发和诱变诱导分离株中，74个具有对环磷酸腺苷依赖性激活的表观活化常数（KaS）增加的激酶。“Ka”表型总是与一个R亚基等位基因中的表观结构损伤相关。通过对部分蛋白酶解肽进行二维凝胶分析，将43个独立分离株中的“电荷转移”损伤定位到R亚基内的小区域。通过突变R亚基的电荷或肽图差异区分出9个Ka突变，这些突变聚集在与R亚基环磷酸腺苷结合位点相关的两个区域。不同突变的相对频率在自发、甲磺酸乙酯诱导和N-甲基-N'-硝基-N-亚硝基胍诱导的分离株中有所不同。两个R亚基等位基因的突变频率也明显不同；这种等位基因偏好对于诱变诱导的更靠近羧基末端的环磷酸腺苷结合位点的损伤最为明显。
