Analysis and mapping of plastin phosphorylation.
Plastins (fimbrins) are a family of three tissue-specific actin-binding proteins. Both L- and T-plastin have been shown to be involved in cytoskeletal reorganization in signal-transduction pathways. Phosphorylation of the leukocyte-specific L-plastin plays important roles in regulating L-plastin function and leukocyte activation. We created L-plastin mutants, changing each of the Ser-5 and Ser-7 residues to alanine. Expression of either mutant in WI38VA13 fibroblasts did not result in phosphorylation. The transfected wildtype L-plastin was phosphorylated in WI38VA13, but its two-dimensional gel pattern suggested that it was phosphorylated on one residue, whereas the endogenous L-plastin in leukocytes was likely phosphorylated on two residues. The nonleukocyte-specific T-plastin, which has an equivalent Ser-7 residue, was not phosphorylated in T-plastin-expressing fibroblasts or in transfected leukocytes. Expression of CK-IIalpha, the catalytic subunit of casein kinase II, resulted in changes of the protein expression profile in leukocytes but not the phosphorylation status of L- or T-plastin. Phorbol myristate acetate induced L-plastin phosphorylation in both leukocytes and fibroblasts, lending support to the view that protein kinase C is the likely candidate kinase for L-plastin phosphorylation.
Lin
C S
CS
Department of Urology, University of California, San Francisco 94143, USA.
Lau
A
A
Lue
T F
TF
D000595:Amino Acid Sequence; D001483:Base Sequence; D047390:Casein Kinase II; D002460:Cell Line; D017931:DNA Primers; D005347:Fibroblasts / Q000187:drug effects / Q000378:metabolism; D006801:Humans; D007962:Leukocytes / Q000187:drug effects / Q000378:metabolism; D008562:Membrane Glycoproteins; D008840:Microfilament Proteins; D016297:Mutagenesis, Site-Directed; D010750:Phosphoproteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D010766:Phosphorylation; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism; D012694:Serine / Q000378:metabolism; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D014407:Tumor Cells, Cultured
D017931:DNA Primers; D008562:Membrane Glycoproteins; D008840:Microfilament Proteins; D010750:Phosphoproteins; C026742:plastin; D012694:Serine; D047390:Casein Kinase II; D017346:Protein Serine-Threonine Kinases; D013755:Tetradecanoylphorbol Acetate