Anchoring mechanisms for LFA-3 cell adhesion glycoprotein at membrane surface.

The manner in which a membrane protein is anchored to the lipid bilayer may have a profound influence on its function. Most cell surface membrane proteins are anchored by a membrane-spanning segment(s) of the polypeptide chain, but another type of anchor has been described for several proteins: a phosphatidyl inositol glycan moiety, attached to the protein C terminus. This type of linkage has been identified on membrane proteins involved in adhesion and transmembrane signalling and could be important in the execution of these functions. We report here that an immunologically important adhesion glycoprotein, lymphocyte function-associated antigen 3 (LFA-3), can be anchored to the membrane by both types of mechanism. These two distinct cell-surface forms of LFA-3 are derived from different biosynthetic precursors. The existence of a phosphatidyl-inositol-linked and a transmembrane anchored form of LFA-3 has important implications for adhesion and transmembrane signalling by LFA-3

pH-Sensitive Nanostructural Transformation of a Synthetic Self-Assembling Water-Soluble Tripeptide: Nanotube to Nanovesicle

Construction of various nanostructures using suitable self-assembling molecular building blocks is a challenging issue. Moreover, controlling the formation of a specific nanostructure from self-assembling molecular building blocks by tuning the pH of the solution is interesting. The present study demonstrates pH-responsive nanostructural transformation of a self-assembling water-soluble tripeptide from nanotubes to nanovesicles. In acidic pH (pH 4.3–5.5), hollow nanotubular structures have been observed, while at pH 6.5 (nearly neutral), both nanotubes and nanovesicles coexist uniformly. With an increase in the pH of the solution, only one nanoscopic species, i.e., nanovesicles, has been formed exclusively, and these hollow, fusible nanovesicles are stable within the range pH 7.0–9.2. A further increase in the pH triggers the rupture of these nanovesicles. pH-sensitive nanovesicle formation has been utilized for the entrapment and slow release of a physiological dye, Congo red