The gene encoding the erythrocyte membrane skeleton protein dematin (Epb4.9) maps to mouse chromosome 14
- Harvard Medical School, Boston, MA (United States)
- Tufts Univ. School of Medicine, Boston, MA (United States); and others
The mammalian erythrocyte membrane skeleton primarily consists of spectrin, actin, protein 4.1 (numerals refer to electrophoretic mobility on SDS-PAGE gels), and dematin (protein 4.9). Although the functional interactions of spectrin, actin, and protein 4.1 have been extensively characterized, virtually nothing is known about the physiological role of dematin. Spectrin is present as elongated heterodimers of {alpha}- and {beta}-subunits arranged in a two-dimensional array just beneath the plasma membrane. The mechanism by which the {open_quotes}head{close_quotes} region of the spectrin dimer binds to the plasma membrane via ankyrin and band 3 is well established. However, the mechanism by which the {open_quotes}tail{close_quotes} end of spectrin is anchored to the plasma membrane is not completely understood. The region containing the spectrin tails is called the junctional complex. Protein 4.1, actin, adducin, and dematin have been directly visualized as components of junctional complexes. Other components of junctional complexes include tropomyosin, tropomodulin, and p55. Protein 4.1 acts as an adaptor protein, linking spectrin-actin complexes to the plasma membrane. Dematin binds actin and therefore also may function as an adaptor protein in mature erythrocytes. Dematin also displays phosphorylation-dependent actin bundling activity. Since actin bundles appear to be absent from mature erythrocytes, this property may be most relevant during erythropoiesis and in nonerythroid cells. The cDNA sequence of human dematin shows significant identity with the {open_quotes}headpiece{close_quotes} of villin, an actin bundling protein of brush border cytoskeleton. Unlike villin, dematin is a widely distributed protein and may substitute for villin to regulate actin bundling events by a phosphorylation-dependent mechanism. 18 refs., 1 fig.
- OSTI ID:
- 209955
- Journal Information:
- Genomics, Journal Name: Genomics Journal Issue: 3 Vol. 26; ISSN 0888-7543; ISSN GNMCEP
- Country of Publication:
- United States
- Language:
- English
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