Changes in Topography of Cell Adhesion Molecules during Lymphocyte Migration Across Endothelium

The widely expressed CD44 single-chain transmembrane glycoprotein has been the object of recent studies in the fields of cell adhesion and lymphocyte activation. This molecule commonly occurs as a 37-kDa polypeptide extensively glycosylated with N- and O-linked oligosaccharides and glycosaminoglycans which migrates in SDS-PAGE as an 80–95-kDa major component of the membranes of most cell types examined (1–3). Higher-molecular-weight forms bearing chondroitin sulfate have been described in lymphoid cells. In other cell types alternately spliced iso-forms possessing an additional extracellular domain exon of 132 or 162 amino acids have been detected (4,5).