Fleming N, Mellow L
Department of Oral Biology, University of Manitoba, Winnipeg, Canada.
Life Sci. 1995;57(22):2003-10. doi: 10.1016/0024-3205(95)02196-p.
The distribution of six isoforms of protein kinase C (PKC) in seromucous acinar cells of rat submandibular gland was examined and their translocation from the cytosolic- to the membrane fraction after different stimuli investigated. Western blotting, immunostaining with isoform-specific antibodies and scanning densitometry showed that PKC-alpha and epsilon were distributed fairly evenly between the cytosol and membranes in resting cells, while isoforms- beta, delta and zeta were all predominantly localized (over 80%) in membranes. PKC-gamma was not detected. PKC-alpha was mobilized to the membrane fraction by the phorbol ester, TPA, but not by the phosphoinositide-coupled agonists carbachol, methoxamine and substance P (SP). PKC-epsilon was translocated by TPA and carbachol but not by SP or methoxamine. Biochemical assay of total PKC confirmed that cytosolic enzyme activity was significantly reduced by TPA and carbachol to 29% and 75% respectively of control levels. These results suggest that muscarinic regulation of the mucosecretory response in the rat submandibular gland may be mediated by the PKC-epsilon isoform.
研究了蛋白激酶C（PKC）六种同工型在大鼠颌下腺浆液性腺泡细胞中的分布，并研究了不同刺激后它们从胞质组分向膜组分的转位情况。蛋白质免疫印迹法、用同工型特异性抗体进行免疫染色以及扫描光密度测定法显示，在静息细胞中，PKC-α和ε在胞质溶胶和膜之间分布相当均匀，而β、δ和ζ同工型主要定位于（超过80%）膜中。未检测到PKC-γ。佛波酯TPA可使PKC-α转位至膜组分，但磷酸肌醇偶联激动剂卡巴胆碱、甲氧明和P物质（SP）则不能。TPA和卡巴胆碱可使PKC-ε转位，但SP或甲氧明则不能。总PKC的生化分析证实，TPA和卡巴胆碱可使胞质酶活性分别显著降低至对照水平的29%和75%。这些结果表明，大鼠颌下腺黏液分泌反应的毒蕈碱调节可能由PKC-ε同工型介导。
