Grinde B, Jonassen T O
Department of Biology, University of Oslo, Norway.
Exp Cell Res. 1987 Dec;173(2):496-503. doi: 10.1016/0014-4827(87)90289-8.
The ciliate Tetrahymena thermophila responds to starvation by drastically increasing the rate of proteolysis. The response was reversed by resuspending the cells in a defined growth medium. Among the components of this medium only amino acids were active in inhibiting proteolysis. One amino acid, methionine, accounted for at least 75% of the effect of the complete medium, strongly indicating that in Tetrahymena methionine is the main regulator of step-down proteolysis, a process generally connected with autophagy in eukaryotic cells. The fact that one amino acid has such a drastic effect should make the system well suited for further investigations of the regulation of this process.
嗜热四膜虫通过大幅提高蛋白水解速率来应对饥饿。将细胞重悬于特定生长培养基中可逆转这种反应。在该培养基的成分中，只有氨基酸能有效抑制蛋白水解。其中一种氨基酸，甲硫氨酸，至少占完全培养基作用的75%，这有力地表明在四膜虫中，甲硫氨酸是降调蛋白水解的主要调节因子，该过程通常与真核细胞中的自噬相关。一种氨基酸能产生如此显著的影响，这一事实应使该系统非常适合进一步研究这一过程的调控。
