Human T cell L-plastin bundles actin filaments in a calcium-dependent manner.
The amino acid sequences deduced from cDNA analyses revealed that human leucocyte L-plastin phosphorylated in response to interleukin 1, 2 closely resembles a chicken intestinal microvilli protein, fimbrin, that bundles actin filaments [de Arruda et al. (1990) J. Cell Biol. 111, 1069-1079]. In the present work, it was observed that unphosphorylated L-plastin isolated from human T cells bundled F-actin just as fimbrin does. L-Plastin acted on T cell beta-actin, but hardly acted on muscle alpha-actin or chicken gizzard gamma-actin, whereas fimbrin bundled muscle alpha-actin. Unlike fimbrin, L-plastin's actin-bundling action was strictly calcium-dependent: the bundles were formed at pCa 7, but not at pCa 6. Under suitable conditions, approximately one molecule of L-plastin bound to 8 molecules of actin monomer in the actin filament.
Namba
Y
Y
Department of Cell Biology, Kyoto University.
Ito
M
M
Zu
Y
Y
Shigesada
K
K
Maruyama
K
K
D008841:Actin Cytoskeleton / Q000187:drug effects* / Q000502:physiology; D000199:Actins / Q000378:metabolism / Q000502:physiology*; D000818:Animals; D002118:Calcium / Q000494:pharmacology*; D006801:Humans; D008562:Membrane Glycoproteins / Q000494:pharmacology / Q000502:physiology; D008840:Microfilament Proteins; D010750:Phosphoproteins / Q000378:metabolism / Q000494:pharmacology*; D011485:Protein Binding; D011817:Rabbits; D013601:T-Lymphocytes / Q000737:chemistry*
D000199:Actins; D008562:Membrane Glycoproteins; D008840:Microfilament Proteins; D010750:Phosphoproteins; C026742:plastin; D002118:Calcium