Ankyrin
A NEW ANKYRIN GENE WITH NEURAL-SPECIFIC ISOFORMS LOCALIZED AT THE AXONAL INITIAL SEGMENT AND NODE OF RANVIER (*)
- From the Howard Hughes Medical Institute and Departments of Cell Biology and Biochemistry, Duke University Medical Center, Durham, North Carolina 27710
- ** To whom correspondence and reprint requests should be addressed. Tel.: 919-684-3105; Fax: 919-684-3590.
Abstract
We have characterized a new ankyrin gene, expressed in brain and other tissues, that is subject to extensive tissue-specific alternative mRNA processing. The full-length polypeptide has a molecular mass of 480 kDa and includes a predicted globular head domain, with membrane- and spectrin-binding activities, as well as an extended “tail” domain. We term this gene ankyrinG based on its giant size and general expression. Two brain-specific isoforms of 480 kDa and 270 kDa were identified that contain a unique stretch of sequence highly enriched in serine and threonine residues immediately following the globular head domain. Antibodies against the serine-rich domain and spectrin-binding domain revealed labeling of nodes of Ranvier and axonal initial segments. Ankyrin-binding proteins also known to be localized in these specialized membrane domains include the voltage-dependent sodium channel, the sodium/potassium ATPase, sodium/calcium exchanger, and members of the neurofascin/L1 family of cell adhesion molecules. The neural-specific ankyrinG polypeptides are candidates to participate in maintenance/targeting of ion channels and cell adhesion molecules to nodes of Ranvier and axonal initial segments.
Footnotes
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↵§ Both authors contributed equally to this work.
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↵¶ Supported by a postdoctoral fellowship from the National Multiple Sclerosis Society. Present address: Department of Supramolecular and Cellular Biology, Institute Jacques Monod, University of Paris, Paris, France. Tel.: 33-1-4427-4223.
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↵* This research is funded in part by National Institutes of Health Grant 537DK29808. The costs of publication of this article were defrayed in part by the payment of page charges. This article must therefore by hereby marked “advertisement” in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.
The nucleotide sequence(s) reported in this paper has been submitted to the GenBank™/EMBL Data Bank with accession number(s) U13616[GenBank].
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↵1 The abbreviations used are:
- kb
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kilobase(s)
- bp
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base pair(s).
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- Received October 31, 1994.
- © 1995 by The American Society for Biochemistry and Molecular Biology, Inc.
