| Autor: |
Vladimir N. Smirnov, G.P. Samokhin, L.V. Lizlova, J.D. Bespalova, M.I. Titov |
| Rok vydání: |
1981 |
| Předmět: |
|
| Zdroj: |
Experimental Cell Research. 131:267-275 |
| ISSN: |
0014-4827 |
| DOI: |
10.1016/0014-4827(81)90231-7 |
| Popis: |
The rate of cell-cycle initiation was studied in a -cells of S. cerevisiae in the presence of the synthetic analogue of α-factor [N-Trp, Arg 7 ]-α-factor (TA-αF). It was shown that TA-αF lowers the rate constant of cell-cycle initiation (or transition probability) for each separate cell. It was concluded on the basis of these results that the term ‘arrest’ in G1 by α-factor should be interpreted in a quantitative sense as the decrease in the probability of the emergence from ‘start’ per unit time and not as being equivalent to an ‘all-or-none’ response. The dependence of the rate constant of the cell-cycle initiation on the concentration of TA-αF can be described by the Hill equation where n = 1.01 + 0.05 and K = 14.5 ± 2.5 nM (±S.E.). It is demonstrated that after transfer of cells into the medium with a higher or a lower concentration of TA-αF, the rate constant of cell-cycle initiation changes abruptly from one value to another after a lag-period of 30 and 40 min respectively. This suggests a multistep mechanism of action for α-factor. The difference in the lag-periods allows us to suggest that α-factor exerts its action by two independent pathways. Since the Hill coefficient is practically equal to unit, no cooperative interactions are likely to be involved at least in one of these pathways. The inhibition of cell-cycle initiation can be used as a more adequate and sensitive test for biological activity of α-factor as compared to morphological measurements. |
| Databáze: |
OpenAIRE |
| Externí odkaz: |
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