Recruitment of a specific amoeboid myosin I isoform to the plasma membrane in chemotactic Dictyostelium cells.
The Dictyostelium class I myosins, MyoA, -B, -C, and -D, participate in plasma membrane-based cellular processes such as pseudopod extension and macropinocytosis. Given the existence of a high affinity membrane-binding site in the C-terminal tail domain of these motor proteins and their localized site of action at the cortical membrane-cytoskeleton, it was of interest to determine whether each myosin I was directly associated with the plasma membrane. The membrane association of a myosin I heavy chain kinase that regulates the activity of one of the class I myosins, MyoD was also examined. Cellular fractionation experiments revealed that the majority of the Dicyostelium MyoA, -B, -C and -D heavy chains and the kinase are cytosolic. However, a small, but significant, fraction (appr. 7. -15%) of each myosin I and the kinase was associated with the plasma membrane. The level of plasma membrane-associated MyoB, but neither that of MyoC nor MyoD, increases up to 2-fold in highly motile, streaming cells. These results indicate that Dictyostelium specifically recruits myoB to the plasma membrane during directed cell migration, consistent with its known role in pseudopod formation.
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Department of Cell Biology, Duke University Medical Center, Durham, North Carolina 27710, USA.
Lee
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Côté
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Titus
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D000599:Amino Acids, Diamino; D000818:Animals; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000378:metabolism*; D002462:Cell Membrane / Q000378:metabolism*; D002465:Cell Movement; D002633:Chemotaxis / Q000502:physiology*; D004023:Dictyostelium / Q000502:physiology*; D020409:Molecular Motor Proteins; D009154:Mutation; D009218:Myosins / Q000235:genetics / Q000378:metabolism*; D011485:Protein Binding; D020033:Protein Isoforms / Q000235:genetics / Q000378:metabolism; D017434:Protein Structure, Tertiary; D015800:Protozoan Proteins / Q000235:genetics / Q000378:metabolism*
D000599:Amino Acids, Diamino; D020409:Molecular Motor Proteins; D020033:Protein Isoforms; D015800:Protozoan Proteins; D017871:Calcium-Calmodulin-Dependent Protein Kinases; C033142:myosin-heavy-chain kinase; D009218:Myosins