UMMS Affiliation
Department of Cell Biology
Date
9-1-1994
Document Type
Article
Subjects
Actins; Animals; Carrier Proteins; Cell Membrane; Dictyostelium; Freeze Fracturing; Fungal Proteins; Microfilament Proteins; Mutation; Phagocytosis; Pinocytosis
Disciplines
Cell Biology | Life Sciences | Medicine and Health Sciences
Abstract
Interactions between the plasma membrane and underlying actin-based cortex have been implicated in membrane organization and stability, the control of cell shape, and various motile processes. To ascertain the function of high affinity actin-membrane associations, we have disrupted by homologous recombination the gene encoding ponticulin, the major high affinity actin-membrane link in Dictyostelium discoideum amoebae. Cells lacking detectable amounts of ponticulin message and protein also are deficient in high affinity actin-membrane binding by several criteria. First, only 10-13% as much endogenous actin cosediments through sucrose and crude plasma membranes from ponticulin-minus cells, as compared with membranes from the parental strain. Second, purified plasma membranes exhibit little or no binding or nucleation of exogenous actin in vitro. Finally, only 10-30% as much endogenous actin partitions with plasma membranes from ponticulin-minus cells after these cells are mechanically unroofed with polylysine-coated coverslips. The loss of the cell's major actin-binding membrane protein appears to be surprisingly benign under laboratory conditions. Ponticulin-minus cells grow normally in axenic culture and pinocytose FITC-dextran at the same rate as do parental cells. The rate of phagocytosis of particles by ponticulin-minus cells in growth media also is unaffected. By contrast, after initiation of development, cells lacking ponticulin aggregate faster than the parental cells. Subsequent morphogenesis proceeds asynchronously, but viable spores can form. These results indicate that ponticulin is not required for cellular translocation, but apparently plays a role in cell patterning during development.
Rights and Permissions
Citation: J Cell Biol. 1994 Sep;126(6):1433-44. Link to article on publisher's website
Related Resources
PubMed ID
8089176
