CD44 is an abundant, widely expressed transmembrane glycoprotein which can act as a receptor for the extracellular matrix glycosaminoglycan, hyaluronan. Biochemical and morphological studies have demonstrated that in fibroblasts a significant of the CD44 population is resistant to Triton X-100 extraction and that the detergent insoluble protein is co-localized with components of the cortical cytoskeleton. Surprisingly, this distribution is not abrogated upon deletion of the CD44 cytoplasmic tail indicating that mechanisms other than a direct interaction with the cytoskeleton can regulate CD44. In this manuscript, the mechanisms underlying this detergent-insoluble association are further investigated. There was no evidence that the Triton X-100 insolubility of CD44 resulted from homotypic aggregation, an association with hyaluronan or from a direct, or indirect, association with the cytoskeleton. Instead, evidence is presented that the detergent insolubility of fibroblast CD44 at 4 degrees C results from an association of the CD44 transmembrane domain with Triton X-100 resistant, lipid rich, plasma membrane domains. The proportion of the CD44 found in these Triton X-100 insoluble structures is dependent upon cell type and cannot be altered by changing cell motility or extracellular matrix associations. These studies provide evidence for a novel mechanism regulating this adhesion protein in the plasma membrane.
CD44 exhibits a cell type dependent interaction with triton X-100 insoluble, lipid rich, plasma membrane domains
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S.J. Neame, C.R. Uff, H. Sheikh, S.C. Wheatley, C.M. Isacke; CD44 exhibits a cell type dependent interaction with triton X-100 insoluble, lipid rich, plasma membrane domains. J Cell Sci 1 September 1995; 108 (9): 3127–3135. doi: https://doi.org/10.1242/jcs.108.9.3127
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