Tension generation by actomyosin thread from a non-muscle system.

A suitable motility model reconstituted from non-muscle contractile proteins should offer a powerful tool for analysing the molecular events in cell motility. Actomyosin thread has been thought to be such a model. As far as non-muscle motile systems are concerned, however, only a very limited number of experiments have been done in this direction. No direct measurement of the tension produced by non-muscular actomyosin thread has been reported in spite of its importance for quantitative studies. We now report that a segment of actomyosin thread of Physarum polycephalum can generate a considerable amount of tension, which is a function of the micromolar concentration of ATP. The maximum isometric tension was a high as 10 g cm-2 at 10 microM ATP.