Viscometric analysis of the gelation of Acanthamoeba extracts and purification of two gelation factors.
Open Access
- 1 May 1980
- journal article
- research article
- Published by Rockefeller University Press in The Journal of cell biology
- Vol. 85 (2), 414-428
- https://doi.org/10.1083/jcb.85.2.414
Abstract
We have studied the kinetics of the gelation process that occurs upon warming cold extracts of Acanthamoeba using a low-shear falling ball assay. We find that the reaction has at least two steps, requires 0.5 mM ATP and 1.5 mM MgCl2, and is inhibited by micromolar Ca++. The optimum pH is 7.0 and temperature, 25 degrees-30 degrees C. The rate of the reaction is increased by cold preincubation with both MgCl2 and ATP. Nonhydrolyzable analogues of ATP will not substitute for ATP either in this "potentiation reaction" or in the gelation process. Either of two purified or any one of four partially purified Acanthamoeba proteins will cross-link purified actin to form a gel, but none can account for the dependence of the reaction in the crude extract on Mg-ATP or its regulation by Ca++. This suggests that the extract contains, in addition to actin-cross-linking proteins, factors dependent on Mg-ATP and Ca++ that regulate the gelation process.This publication has 22 references indexed in Scilit:
- The contractile basis of amoeboid movement *1IV. The viscoelasticity and contractility of amoeba cytoplasm in vivoExperimental Cell Research, 1977
- Purification from Acanthamoeba castellanii of proteins that induce gelation and syneresis of F-actin.Journal of Biological Chemistry, 1977
- Characterization of cytoplasmic actin isolated from Acanthamoeba castellanii by a new method.Journal of Biological Chemistry, 1976
- Preparation and purification of polymerized actin from sea urchin egg extracts.The Journal of cell biology, 1975
- Regulatory proteins of lobster striated muscleBiochemistry, 1975
- Rheology of F-actin I. Network of F-actin in solutionBiochimica et Biophysica Acta (BBA) - Protein Structure, 1974
- THE CONTRACTILE BASIS OF AMOEBOID MOVEMENTThe Journal of cell biology, 1973
- Determination of protein: A modification of the lowry method that gives a linear photometric responseAnalytical Biochemistry, 1972
- The regulation of rabbit skeletal muscle contraction. I. Biochemical studies of the interaction of the tropomyosin-troponin complex with actin and the proteolytic fragments of myosin.1971
- CYTOPLASMIC FILAMENTS OF AMOEBA PROTEUS The Journal of cell biology, 1970