INVESTIGADORES
BARRANTES Francisco Jose
artículos
Título:
Asymmetric distribution of phospholipids in acetylcholine receptor-rich membranes from Torpedo marmorata electric organ
Autor/es:
BONINI I,; BARRANTES FJ; AVELDAÑO MI,
Revista:
INTERNATIONAL JOURNAL OF BIOCHEMISTRY AND CELLULAR BIOLOGY
Editorial:
PERGAMON-ELSEVIER SCIENCE LTD
Referencias:
Lugar: Amsterdam; Año: 1990 vol. 22 p. 785 - 789
ISSN:
1357-2725
Resumen:
1.
The distribution of phospholipids between the two leaflets of the lipid
bilayer in acetylcholine receptor (AChR)-rich membranes from T. marmorata
has been examined with two complementary techniques: chemical
derivatization with the membrane-impermeable reagent
trinitrobenzenesulphonate (TNBS) and B. cereus phospholipase C hydrolysis.2.
AChR-membranes were reacted with TNBS at 0?4 and 37°C and the
accessibility of their aminophospholipids was compared to that of rod
outer segment and erythrocyte membranes. The results indicate that more
of the total ethanolamine glycerophospholipid (EGP) than of the total
phosphatidylserine (PS) is located in the outer monolayer.3. Nearly half the phospholipid content of AChR membranes is hydrolyzed by phospholipase C with a half-time of ca
1.6 min at 25°C. Consistent with the TNBS results, more of the total
EGP than of the total PS is degraded. Beyond 3 min the reaction slows
down, relatively smaller additional amounts of lipids are hydrolyzed, and all
phospholipid classes are attacked to a similar extent, indicating that
after half the lipid is removed all phospholipids become accessible to
the enzyme.4. The results
indicate that the outer leaflet of the bilayer is richer in
ethanolamine and choline glycerophospholipids, whereas
phosphatidylinositol, most of the sphingomyelin, and ca 65% of the PS are located on the inner leaflet.