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Influence of cholesterol crystallization effector proteins on vesicle fusion in supersaturated model bile[Note 1. Parts of this study were presented at the Annual ...]
Author(s) -
Hattori Yoshihiro,
Tazuma Susumu,
Yamashita Gunji,
Kajiyama Goro
Publication year - 1999
Publication title -
journal of gastroenterology and hepatology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.214
H-Index - 130
eISSN - 1440-1746
pISSN - 0815-9319
DOI - 10.1046/j.1440-1746.1999.01933.x
Subject(s) - vesicle , cholesterol , liposome , concanavalin a , lipid bilayer fusion , apolipoprotein b , biochemistry , phospholipid , chemistry , microbiology and biotechnology , biophysics , biology , membrane , in vitro
Background : In lithogenic bile, cholesterol‐rich vesicles rapidly aggregate and fuse to eventually form cholesterol crystals. This process is modulated by cholesterol crystallization effector substances. In this study, we developed a method for quantitative assessment of vesicle fusion and used it to partly characterize the mechanisms of action of cholesterol crystallization effector proteins. Methods : Cholesterol:phospholipid (1:1) liposomes were prepared and labelled with octadecyl rhodamine B chloride (R18). Fusion of these liposomes was detected by the increase of R18 fluorescence after incubation with various proteins, such as albumin, concanavalin‐A bound glycoprotein, immunoglobulins, apolipoprotein A‐I and apolipoprotein B (all at 100 μg/mL). Results : Fusion of cholesterol/phospholipid liposomes was increased by 16 and 14% in the presence of concanavalin‐A bound glycoprotein and immunoglobulins, respectively, and decreased by 21 and 9% after addition of apolipoprotein A‐I and apolipoprotein B, respectively. The effect of each protein on vesicle fusion was correlated with its hydrophobicity. Conclusions : These results suggest that nucleation effector proteins modulate the stability of vesicles and, thus, affect cholesterol crystallization. Such modulation is based upon protein–vesicle association, which defines the physico‐chemical metastability of vesicular cholesterol.