Location of Repository

Differential localization of Acanthamoeba myosin I isoforms



Acanthamoeba myosins IA and IB were localized by immunofluorescence and immunoelectron microscopy in vegetative and phagocytosing cells and the total cell contents of myosins IA, IB, and IC were quantified by immunoprecipitation. The quantitative distributions of the three myosin I isoforms were then calculated from these data and the previously determined localization of myosin IC. Myosin IA occurs almost exclusively in the cytoplasm, where it accounts for approximately 50% of the total myosin I, in the cortex beneath phagocytic cups and in association with small cytoplasmic vesicles. Myosin IB is the predominant isoform associated with the plasma membrane, large vacuole membranes and phagocytic membranes and accounts for almost half of the total myosin I in the cytoplasm. Myosin IC accounts for a significant fraction of the total myosin I associated with the plasma membrane and large vacuole membranes and is the only myosin I isoform associated with the contractile vacuole membrane. These data suggest that myosin IA may function in cytoplasmic vesicle transport and myosin I-mediated cortical contraction, myosin IB in pseudopod extension and phagocytosis, and myosin IC in contractile vacuole function. In addition, endogenous and exogenously added myosins IA and IB appeared to be associated with the cytoplasmic surface of different subpopulations of purified plasma membranes implying that the different myosin I isoforms are targeted to specific membrane domains through a mechanism that involves more than the affinity of the myosins for anionic phospholipids

Topics: Articles
Publisher: The Rockefeller University Press
OAI identifier: oai:pubmedcentral.nih.gov:2289716
Provided by: PubMed Central
Download PDF:
Sorry, we are unable to provide the full text but you may find it at the following location(s):
  • http://www.pubmedcentral.nih.g... (external link)
  • Suggested articles



    1. (1988). A novel 190 kDa calmodulinbinding protein associated with brain actomyosin.
    2. (1991). Acanthamoeba myosin I: past, present, and future.
    3. (1973). Acanthamoeba myosin. I. Isolation from Acanthamoeba castellanii of an enzyme similar to muscle myosin.
    4. (1984). Aeanthamoeba myosin IA, IB, and II heavy chains are synthesized in vitro fromAcanthamoeba messenger RNA.
    5. (1988). Antibodies. A laboratory manual.
    6. (1986). ATPase activities and actin-binding properties of subfragments of Acanthamoeba myosin IA.
    7. (1989). Binding of myosin I to membrane lipids.
    8. (1990). Calmodulinbinding proteins and calcium/calmodulin-regulated enzyme activities associated with brain actomyosin.
    9. (1986). Characterization of monoelonal antibodies to Acanthamoeba myosin-I that cross-react with both myosin-I/and low molecular weight nuclear proteins.
    10. (1970). Cleavage of structural proteins during the assembly of the head of bacteriophage T4.
    11. (1979). Electrophoretic transfer of proteins from polyacrylamide gels to nitrocellulose sheets: procedure and some applications.
    12. (1980). Evidence for differential intracellular localization of the Acanthamoeba myosin isoenzymes.
    13. (1991). Immunolocalization of myosin I heavy chain kinase in Acanthamoeba castellanii and binding of purified kinase to isolated plasma membranes.
    14. (1990). Localization of myosin IC and myosin II in Acanthamoeba castellanii by indirect immunofluorescence and immunogold electron microscopy.
    15. (1992). Localization of the actinbinding sites of Acanthamoeba myosin IB and effect of limited proteolysis on its aetin-activated Mg2*-ATPase activity.
    16. (1981). Morphometric analysis of volumes and surface areas in membrane compartments during endoeytosis in Acanthamoeba.
    17. (1989). Myosin I is located at the leading edges of locomoting Dictyostelium amoebae.
    18. (1988). Myosins of non-muscle cells.
    19. (1991). Novel myosin heavy chain encoded by murine dilute coat colour locus.
    20. (1988). Organization of the actin filament cytoskeleton in the intestinal brush border: a quantitative and qualitative immunoelectron microscope study.
    21. (1989). Plasma membrane association of Acanthamoeba myosin
    22. (1992). Purification and characterization of a mammalian myosin I.
    23. (1983). Purification and characterization of a myosin I heavy chain kinase from Acanthamoeba castellanii.
    24. (1989). Purification and characterization of a third isoform of myosin I from Acanthamoeba castellanii,
    25. (1991). Purification of myosin I and myosin I heavy chain ldnase from Acanthamoeba castellanii. Methods Enzymol.
    26. (1988). Purification of plasma membrane from Acanthamoeba castellanii.
    27. (1990). Size selection identifies new genes that regulate Saccharomyces cerevisiae cell proliferation.
    28. (1988). The Drosophila ninaC locus encodes two photoreceptor cell specific proteins with domains homologous to protein kinases and the myosin heavy chain head.
    29. (1987). The heavy chain of Acanthamoeba myosin IB is a fusion of myosin-like and non-myosin-like sequences.
    30. (1989). The localization and sequence of the phosphorylation sites of Acanthamoeba myosins I.
    31. (1981). Use of protein A-beating staphylococci for the immunoprecipitation and isolation of antigens from cells. Methods Enzymol.

    To submit an update or takedown request for this paper, please submit an Update/Correction/Removal Request.