首页 | 本学科首页   官方微博 | 高级检索  
   检索      


Treadmilling of actin at physiological salt concentrations: An analysis of the critical concentrations of actin filaments
Authors:Albrecht Wegner
Institution:Department of Physiological Chemistry I Ruhr-University Bochum Universitaetsstrasse 150 D-4630 Bochum, Federal Republic of Germany
Abstract:Treadmilling of actin was investigated at physiological salt concentrations (100 mm-KCl, 0.5 to 2.0 mm-MgCl2, 200 μm-ethyleneglycol-bis(β-aminoethyl ether)N,N′-tetraacetic acid or 50 μm-CaCl2 at 37 °C. The concentration at which monomers bind to the lengthening end of filaments with the same rate as subunits are released (low critical concentration c1 was determined by mixing unmodified actin filaments with various concentrations of monomeric actin labeled with 7-chloro-4-nitrobenzo-2-oxa-1,3-diazole. Above a monomeric actin concentration of about 0.12 μm, incorporation of actin molecules into filaments was detected, whereas below this concentration no incorporation was found (c1 = 0.12 μm). Combination of various concentrations of labeled monomers with labeled filaments permitted determination of the net critical concentration (c1) at which filaments lengthen at one end with the same rate as they shorten at the other end (c1 = 0.16 μm). A lower limit of the high critical concentration at the shortening end (ch) was estimated by measuring the release of subunits from labeled filaments in the presence of various concentrations of unlabeled monomers (ch >0.5 μm). The differences in the three critical concentrations demonstrate that under physiological conditions actin filaments lengthen at one end by, on the average, one subunit during the time that four association reactions take place at the two ends (efficiency parameters s = 14). The small difference between the low and the net critical concentration suggests that the rates of both association and dissociation are considerably greater at the lengthening end than at the shortening end of actin filaments.
Keywords:
本文献已被 ScienceDirect 等数据库收录!
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号