Cortexillins, major determinants of cell shape and size, are actin-bundling proteins with a parallel coiled-coil tail.
Cortexillins I and II of D. discoideum constitute a novel subfamily of proteins with actin-binding sites of the alpha-actinin/spectrin type. The C-terminal halves of these dimeric proteins contain a heptad repeat domain by which the two subunits are joined to form a two-stranded, parallel coiled coil, giving rise to a 19 nm tail. The N-terminal domains that encompass a consensus actin-binding sequence are folded into globular heads. Cortexillin-linked actin filaments form preferentially anti-parallel bundles that associate into meshworks. Both cortexillins are enriched in the cortex of locomoting cells, primarily at the anterior and posterior ends. Elimination of the two isoforms by gene disruption gives rise to large, flattened cells with rugged boundaries, portions of which are often connected by thin cytoplasmic bridges. The double-mutant cells are multinucleate owing to a severe impairment of cytokinesis.
Faix
J
J
Max-Planck-Institut für Biochemie, Martinsried, Federal Republic of Germany.
Steinmetz
M
M
Boves
H
H
Kammerer
R A
RA
Lottspeich
F
F
Mintert
U
U
Murphy
J
J
Stock
A
A
Aebi
U
U
Gerisch
G
G
D000199:Actins / Q000378:metabolism; D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D002451:Cell Compartmentation; D048429:Cell Size; D017931:DNA Primers / Q000737:chemistry; D004023:Dictyostelium; D005656:Fungal Proteins / Q000502:physiology; D008840:Microfilament Proteins / Q000502:physiology*; D008854:Microscopy, Electron; D008969:Molecular Sequence Data; D016254:Mutagenesis, Insertional; D017434:Protein Structure, Tertiary; D015800:Protozoan Proteins; D012091:Repetitive Sequences, Nucleic Acid; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid
D000199:Actins; D017931:DNA Primers; D005656:Fungal Proteins; D008840:Microfilament Proteins; D015800:Protozoan Proteins; C101109:ctxA protein, Dictyostelium discoideum; C101110:ctxB protein, Dictyostelium discoideum