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Small, Membrane-bound, Alternatively Spliced Forms of Ankyrin 1 Associated with the Sarcoplasmic Reticulum of Mammalian Skeletal Muscle

We have recently found that the erythroid ankyrin gene, Ank1, expresses isoforms in mouse skeletal muscle, several of which share COOH-terminal sequence with previously known Ank1 isoforms but have a novel, highly hydrophobic 72–amino acid segment at their NH(2) termini. Here, through the use of dom...

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Autores principales: Zhou, Daixing, Birkenmeier, Connie S., Williams, McRae W., Sharp, John J., Barker, Jane E., Bloch, Robert J.
Formato: Texto
Lenguaje:English
Publicado: The Rockefeller University Press 1997
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2134284/
https://www.ncbi.nlm.nih.gov/pubmed/9024692
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author Zhou, Daixing
Birkenmeier, Connie S.
Williams, McRae W.
Sharp, John J.
Barker, Jane E.
Bloch, Robert J.
author_facet Zhou, Daixing
Birkenmeier, Connie S.
Williams, McRae W.
Sharp, John J.
Barker, Jane E.
Bloch, Robert J.
author_sort Zhou, Daixing
collection PubMed
description We have recently found that the erythroid ankyrin gene, Ank1, expresses isoforms in mouse skeletal muscle, several of which share COOH-terminal sequence with previously known Ank1 isoforms but have a novel, highly hydrophobic 72–amino acid segment at their NH(2) termini. Here, through the use of domainspecific peptide antibodies, we report the presence of the small ankyrins in rat and rabbit skeletal muscle and demonstrate their selective association with the sarcoplasmic reticulum. In frozen sections of rat skeletal muscle, antibodies to the spectrin-binding domain (anti-p65) react only with a 210-kD Ank1 and label the sarcolemma and nuclei, while antibodies to the COOH terminus of the small ankyrin (anti-p6) react with peptides of 20 to 26 kD on immunoblots and decorate the myoplasm in a reticular pattern. Mice homozygous for the normoblastosis mutation (gene symbol nb) are deficient in the 210-kD ankyrin but contain normal levels of the small ankyrins in the myoplasm. In nb/nb skeletal muscle, anti-p65 label is absent from the sarcolemma, whereas anti-p6 label shows the same distribution as in control skeletal muscle. In normal skeletal muscle of the rat, anti-p6 decorates Z lines, as defined by antidesmin distribution, and is also present at M lines where it surrounds the thick myosin filaments. Immunoblots of the proteins isolated with rabbit sarcoplasmic reticulum indicate that the small ankyrins are highly enriched in this fraction. When expressed in transfected HEK 293 cells, the small ankyrins are distributed in a reticular pattern resembling the ER if the NH(2)-terminal hydrophobic domain is present, but they are uniformly distributed in the cytosol if this domain is absent. These results suggest that the small ankyrins are integral membrane proteins of the sarcoplasmic reticulum. We propose that, unlike the 210-kD form of Ank1, previously localized to the sarcolemma and believed to be a part of the supporting cytoskeleton, the small Ank1 isoforms may stabilize the sarcoplasmic reticulum by linking it to the contractile apparatus.
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spelling pubmed-21342842008-05-01 Small, Membrane-bound, Alternatively Spliced Forms of Ankyrin 1 Associated with the Sarcoplasmic Reticulum of Mammalian Skeletal Muscle Zhou, Daixing Birkenmeier, Connie S. Williams, McRae W. Sharp, John J. Barker, Jane E. Bloch, Robert J. J Cell Biol Article We have recently found that the erythroid ankyrin gene, Ank1, expresses isoforms in mouse skeletal muscle, several of which share COOH-terminal sequence with previously known Ank1 isoforms but have a novel, highly hydrophobic 72–amino acid segment at their NH(2) termini. Here, through the use of domainspecific peptide antibodies, we report the presence of the small ankyrins in rat and rabbit skeletal muscle and demonstrate their selective association with the sarcoplasmic reticulum. In frozen sections of rat skeletal muscle, antibodies to the spectrin-binding domain (anti-p65) react only with a 210-kD Ank1 and label the sarcolemma and nuclei, while antibodies to the COOH terminus of the small ankyrin (anti-p6) react with peptides of 20 to 26 kD on immunoblots and decorate the myoplasm in a reticular pattern. Mice homozygous for the normoblastosis mutation (gene symbol nb) are deficient in the 210-kD ankyrin but contain normal levels of the small ankyrins in the myoplasm. In nb/nb skeletal muscle, anti-p65 label is absent from the sarcolemma, whereas anti-p6 label shows the same distribution as in control skeletal muscle. In normal skeletal muscle of the rat, anti-p6 decorates Z lines, as defined by antidesmin distribution, and is also present at M lines where it surrounds the thick myosin filaments. Immunoblots of the proteins isolated with rabbit sarcoplasmic reticulum indicate that the small ankyrins are highly enriched in this fraction. When expressed in transfected HEK 293 cells, the small ankyrins are distributed in a reticular pattern resembling the ER if the NH(2)-terminal hydrophobic domain is present, but they are uniformly distributed in the cytosol if this domain is absent. These results suggest that the small ankyrins are integral membrane proteins of the sarcoplasmic reticulum. We propose that, unlike the 210-kD form of Ank1, previously localized to the sarcolemma and believed to be a part of the supporting cytoskeleton, the small Ank1 isoforms may stabilize the sarcoplasmic reticulum by linking it to the contractile apparatus. The Rockefeller University Press 1997-02-10 /pmc/articles/PMC2134284/ /pubmed/9024692 Text en This article is distributed under the terms of an Attribution–Noncommercial–Share Alike–No Mirror Sites license for the first six months after the publication date (see http://www.rupress.org/terms). After six months it is available under a Creative Commons License (Attribution–Noncommercial–Share Alike 4.0 Unported license, as described at http://creativecommons.org/licenses/by-nc-sa/4.0/).
spellingShingle Article
Zhou, Daixing
Birkenmeier, Connie S.
Williams, McRae W.
Sharp, John J.
Barker, Jane E.
Bloch, Robert J.
Small, Membrane-bound, Alternatively Spliced Forms of Ankyrin 1 Associated with the Sarcoplasmic Reticulum of Mammalian Skeletal Muscle
title Small, Membrane-bound, Alternatively Spliced Forms of Ankyrin 1 Associated with the Sarcoplasmic Reticulum of Mammalian Skeletal Muscle
title_full Small, Membrane-bound, Alternatively Spliced Forms of Ankyrin 1 Associated with the Sarcoplasmic Reticulum of Mammalian Skeletal Muscle
title_fullStr Small, Membrane-bound, Alternatively Spliced Forms of Ankyrin 1 Associated with the Sarcoplasmic Reticulum of Mammalian Skeletal Muscle
title_full_unstemmed Small, Membrane-bound, Alternatively Spliced Forms of Ankyrin 1 Associated with the Sarcoplasmic Reticulum of Mammalian Skeletal Muscle
title_short Small, Membrane-bound, Alternatively Spliced Forms of Ankyrin 1 Associated with the Sarcoplasmic Reticulum of Mammalian Skeletal Muscle
title_sort small, membrane-bound, alternatively spliced forms of ankyrin 1 associated with the sarcoplasmic reticulum of mammalian skeletal muscle
topic Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2134284/
https://www.ncbi.nlm.nih.gov/pubmed/9024692
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