Human T Cell L-Plastin Bundles Actin Filaments in a Calcium Dependent Manner

• Published in: Journal of biochemistry (Tokyo) 1992-10, Vol.112 (4), p.503-507
• Main Authors: Namba, Yuziro, Ito, Masaya, Zu, Youli, Shigesada, Katsuya, Maruyama, Koscak
• Format: Article
• Language: English
• Subjects: Actin Cytoskeleton - drug effects; Actin Cytoskeleton - physiology; Actins - metabolism; Actins - physiology; Analytical, structural and metabolic biochemistry; Animals; Biological and medical sciences; Calcium - pharmacology; Fundamental and applied biological sciences. Psychology; Humans; Membrane Glycoproteins - pharmacology; Membrane Glycoproteins - physiology; Microfilament Proteins; Miscellaneous; Phosphoproteins - metabolism; Phosphoproteins - pharmacology; Protein Binding; Proteins; Rabbits; T-Lymphocytes - chemistry
• ISSN: 0021-924X; 1756-2651
• DOI: 10.1093/oxfordjournals.jbchem.a123929

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 β-actin, but hardly acted on muscle γ-actin or chicken gizzard α-actin, whereas fimbrin bundled muscle α-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.