Smith R, Preston R R, Schulz S, Gagnon M L, Van Houten J
Biochim Biophys Acta. 1987 Apr 22;928(2):171-8. doi: 10.1016/0167-4889(87)90118-2.
Paramecium tetraurelia is attracted to cyclic AMP, which probably, as other attractants, signifies the presence of food. Attraction to cyclic AMP was specific, saturable, and, therefore, likely to be receptor-mediated. In these studies, we measured the binding of cyclic [3H]AMP to whole cells and found it to be saturable, reversible, and displaying specificity similar to that of attraction. An HPLC method of separating nucleotides was devised and used to determine that external cyclic AMP was degraded in the absence of IBMX, a phosphodiesterase inhibitor, and that cyclic AMP was taken into the cells in small amounts. Since binding and attraction were subsequently measured in the presence of IMBX, it was cyclic AMP and not a degradation product that served as the attractant stimulus for Paramecium.
四膜虫对环磷酸腺苷（cAMP）有趋化性，与其他引诱剂一样，cAMP可能表明食物的存在。对cAMP的趋化性具有特异性、可饱和性，因此可能是由受体介导的。在这些研究中，我们测量了环[³H]腺苷酸与全细胞的结合，发现其具有可饱和性、可逆性，且显示出与趋化性相似的特异性。我们设计了一种用于分离核苷酸的高效液相色谱法（HPLC），并据此确定在不存在磷酸二酯酶抑制剂异丁基甲基黄嘌呤（IBMX）的情况下，外部cAMP会降解，且细胞会摄取少量的cAMP。由于随后在存在IMBX的情况下测量了结合和趋化性，所以作为四膜虫引诱刺激物的是cAMP而非降解产物。
