Publications [#112819] of G Vann V. Bennett
- W Chan, E Kordeli, V Bennett, 440-kD ankyrinB: structure of the major developmentally regulated domain and selective localization in unmyelinated axons.,
The Journal of cell biology, UNITED STATES, vol. 123 no. 6 Pt 1
pp. 1463-73, ISSN 0021-9525
(last updated on 2003/02/18)
440-kD ankyrinB is an alternatively spliced variant of 220-kD ankyrinB, with a predicted 220-kD sequence inserted between the membrane/spectrin binding domains and COOH-terminal domain (Kunimoto, M., E. Otto, and V. Bennett. 1991. J. Cell Biol. 236:1372-1379). This paper presents the sequence of 2085 amino acids comprising the alternatively spliced portion of 440-kD ankyrinB, and provides evidence that much of the inserted sequence has the configuration of an extended random coil. Notable features of the inserted sequence include a hydrophilicity profile that contains few hydrophobic regions, and 220 predicted sites for phosphorylation by protein kinases (casein kinase 2, protein kinase C, and proline-directed protein kinase). Secondary structure and folding of the inserted amino acid residues were deduced from properties of recombinant polypeptides. Frictional ratios of 1.9-2.4 were calculated from Stokes radii and sedimentation coefficients, for polypeptides comprising 70% of the inserted sequence, indicating a highly asymmetric shape. Circular dichroism spectra of these polypeptides indicate a nonglobular structure with negligible alpha-helix or beta sheet folding. These results suggest a ball-and-chain model for 440-kD ankyrinB with a membrane-associated globular head domain and an extended filamentous tail domain encoded by the inserted sequence. Immunofluorescence and immunoblot studies of developing neonatal rat optic nerve indicate that 440-kD ankyrinB is selectively targeted to premyelinated axons, and that 440-kD ankyrinB disappears from these axons coincident with myelination. Hypomyelinated nerve tracts of the myelin-deficient Shiverer mice exhibit elevated levels of 440-kD ankyrinB. 440-kD ankyrinB thus is a specific component of unmyelinated axons and expression of 440-kD ankyrinB may be downregulated as a consequence of myelination.
Amino Acid Sequence • Animals • Ankyrins • Axons • Binding Sites • Circular Dichroism • Cloning, Molecular • DNA, Complementary • Humans • Mice • Mice, Neurologic Mutants • Molecular Sequence Data • Optic Nerve • Protein Structure, Secondary • Rats • Recombinant Proteins • Solubility • Structure-Activity Relationship • chemistry* • genetics • metabolism • metabolism*