A role for myosin-1A in the localization of a brush border disaccharidase.

Tyska MJ, Mooseker MS
J Cell Biol. 2004 165 (3): 395-405

PMID: 15138292 · PMCID: PMC2172191 · DOI:10.1083/jcb.200310031

To gain insight regarding myosin-1A (M1A) function, we expressed a dominant negative fragment of this motor in the intestinal epithelial cell line, CACO-2BBE. Sucrase isomaltase (SI), a transmembrane disaccharidase found in microvillar lipid rafts, was missing from the brush border (BB) in cells expressing this fragment. Density gradient centrifugation, affinity purification, and immunopurification of detergent-resistant membranes isolated from CACO-2BBE cells and rat microvilli (MV) all indicate that M1A and SI reside on the same population of low density (approximately 1.12 g/ml) membranes. Chemical cross-linking of detergent-resistant membranes from rat MV indicates that SI and M1A may interact in a lipid raft complex. The functional significance of such a complex is highlighted by expression of the cytoplasmic domain of SI, which results in lower levels of M1A and a loss of SI from the BB. Together, these studies are the first to assign a specific role to M1A and suggest that this motor is involved in the retention of SI within the BB.

Copyright the Rockefeller University Press

MeSH Terms (17)

Animals Caco-2 Cells Calmodulin-Binding Proteins Cell Membrane Digestion Disaccharides Fluorescent Antibody Technique Humans Intestinal Mucosa Membrane Microdomains Microvilli Myosin Heavy Chains Myosin Type I Protein Structure, Tertiary Rats Subcellular Fractions Sucrase-Isomaltase Complex

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