Subcellular Distribution and Thermally-Induced Transition of Adenylate Cyclase Activity in Thermotolerant Tetrahymena Surface Membranes

[摘要] References(30)Cited-By(9)The subcellular localization and thermally-induced transition of adenylate cyclase activity were studied in a thermotolerant strain of Tetra-hymena pyriformis. A close relationship was present between adenylate cyclase activity and the cell growth cycle. Maximum cyclase activity was found in early stationary phase cells. Adenylate cyclase activity was found primarily associated with the surface membrane, pellicle, The activity of adenylate cyclase in pellicle membrane was measured as a function of temperature. Arrhenius plots of its membrane activity were found to be triphasic. A marked change occurred at about 28°C and small discontinuities were present at around 15°C. Freeze-cleavage electron microscopic observations of pellicle membranes revealed that membrane-intercalated particles began to form aggregation clusters at decreasing temperatures, and below the transition point (28°C) of cyclase activity a remarkable phase separation was formed. These results from enzymatic and morphological studies of pellicle membranes suggest that the thermally-induced transition of adenylate cyclase activity may reflect altered physical states of membrane lipid caused by temperature changes.

[学科分类] 分子生物学，细胞生物学和基因