Ns. Kumar et Cm. Mansbach, DETERMINANTS OF TRIACYLGLYCEROL TRANSPORT FROM THE ENDOPLASMIC-RETICULUM TO THE GOLGI IN INTESTINE, American journal of physiology: Gastrointestinal and liver physiology, 36(1), 1997, pp. 18-30
The ability of the intestinal cell to export triacylglycerol (TG) is a
physiologically regulatable function. The intracellular site where th
is occurs is un]mown, although available evidence suggests that the st
ep between the endoplasmic reticulum (ER) and the Golgi is the most li
kely. We studied this process in rat enterocytes that were isolated fr
om the proximal intestine. A novel system was developed in which [H-3]
TG was transported from ER to the Golgi. This process was time, ATP, t
emperature, and cytosol dependent. The cytosolic factor(s) was heat an
d trypsin sensitive. TG transport was directly proportional to the amo
unt of added nonradiolabeled acceptor Golgi. The rate of TG transporte
d to tile Golgi was the fastest in cells isolated from rats that had b
een intraduodenally infused in vivo with glyceryltrioleate (TO) plus p
hosphatidylcholine and slowest in cells isolated from bile-fistulated
rats infused with TO in vivo compared with cells from in vivo TO-infus
ed, bile duct intact rats, mimicking the relative transport rates seen
in vivo. TG transport in vitro could not be quenched by adding TG emu
lsions, chylomicrons, liposomes, or guanosine 5'-O-(3-thiotriphosphate
). Cytosol from the liver and kidney supported TG transport, but; the
Golgi from liver or kidney did not accept TG from intestinal ER. We co
nclude that an intestinally specific, active transport mechanism trans
ports TG from the ER to the Golgi and that this might be a regulatory
step in TG export from the intestinal cell.