Coronin forms a stable dimer through its C-terminal coiled coil region: an implicated role in its localization to cell periphery.
BACKGROUND
Coronin is an actin-binding protein, which contains WD (Trp-Asp) repeats and a coiled-coil motif, and plays a role in regulating organization of the actin cytoskeletal network. Coronin localizes to the cell periphery, is involved in lamellipodium extension, and has an implicated role in cytokinesis, cell motility and phagocytosis.


RESULTS
Our experiments with two different tagged forms of Xenopus coronin (Xcoronin) have shown that Xcoronin forms an oligomer. This oligomer complex is stable, resistant to 2.4 M NaCl, 0.6 M KI or 2 M urea. Physiochemical analysis of endogenous Xcoronin and the protein expressed in COS7 cells or in bacteria has revealed that the oligomer complex is an Xcoronin dimer. A C-terminal coiled-coil motif of Xcoronin is necessary and sufficient for the dimerization. Mutations in the coiled-coil motif generated dimerization deficient mutants of Xcoronin. Moreover, these mutant forms of Xcoronin failed to localize to the cell periphery, suggesting that dimerization is important for the proper subcellular localization of Xcoronin.


CONCLUSIONS
Xcoronin forms a stable dimer via its C-terminal coiled-coil region. We propose that coronin dimerization is necessary for its proper subcellular localization and function.
Department of Biophysics, Graduate School of Science, Kyoto University, Sakyo-ku, Japan.
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Asano
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Mishima
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Nishida
D000199:Actins / Q000378:metabolism; D020816:Amino Acid Motifs; D000818:Animals; D019556:COS Cells; D002462:Cell Membrane / Q000235:genetics / Q000378:metabolism / Q000502:physiology; D003593:Cytoplasm / Q000378:metabolism / Q000502:physiology; D019281:Dimerization; D008840:Microfilament Proteins / Q000235:genetics / Q000378:metabolism* / Q000502:physiology; D010446:Peptide Fragments / Q000235:genetics / Q000378:metabolism* / Q000502:physiology; D017434:Protein Structure, Tertiary / Q000235:genetics; D020449:Repetitive Sequences, Amino Acid; D017386:Sequence Homology, Amino Acid; D014162:Transfection; D014981:Xenopus
D000199:Actins; D008840:Microfilament Proteins; D010446:Peptide Fragments; C072061:coronin proteins