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Keywords :
Active Transport, Cell Nucleus; Amino Acid Sequence; Animals; Cell Line; Cell Nucleus/drug effects/metabolism; Cercopithecus aethiops; Fatty Acids, Unsaturated/pharmacology; Gene Products, rev/genetics/metabolism; Humans; Leucine/genetics/metabolism; Membrane Glycoproteins; Microfilament Proteins/metabolism; Molecular Sequence Data; Phenotype; Phenylalanine/genetics/metabolism; Phosphoproteins/genetics/metabolism; Protein Isoforms/metabolism; Protein Sorting Signals/drug effects; Sequence Alignment
Abstract :
[en] T- and L-plastin are highly similar actin-bundling proteins implicated in the regulation of cell morphology, lamellipodium protrusion, bacterial invasion and tumor progression. We show that T-plastin localizes predominantly to the cytoplasm, whereas L-plastin distributes between nucleus and cytoplasm in HeLa or Cos cells. T-plastin shows nuclear accumulation upon incubation of cells with the CRM1 antagonist leptomycin B (LMB). We identified a Rev-like nuclear export sequence (NES) in T-plastin that is able to export an otherwise nuclear protein in an LMB-dependent manner. Deletion of the NES promotes nuclear accumulation of T-plastin. Mutation of residues L17, F21 or L26 in the T-plastin NES inhibits nuclear efflux. L-plastin harbors a less conserved NES and lacks the F21 T-plastin residue. Insertion of a Phe residue in the L-plastin NES specifically enhances its export activity. These findings explain why both isoforms exhibit specific distribution patterns in eukaryotic cells.
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