Functional significance of interaction of H-FABP with sulfated and nonsulfated taurine-conjugated bile salts in rat liver.
J Lipid Res
; 36(8): 1745-55, 1995 Aug.
Article
em En
| MEDLINE
| ID: mdl-7595095
ABSTRACT
To identify the cytosolic proteins of rat hepatocytes involved in transcellular transport of sulfated and taurine-conjugated bile salts in comparison with only taurine-conjugated bile salts, photoaffinity labeling studies were performed with [3H]-7,7-ASLCT (7,7-azi-3 alpha-sulfatolithocholyl[2'-3H(N)]taurine), [3H]-7,7-ACT ((7,7-azi-3 alpha,12 alpha-dihydroxy-5 beta-cholan-24-oyl)- 2'-[2'-3H(N)]aminoethanesulfonate), and [3H]-7,7-ALCT (7,7-azilithocholyl[2'-3H(N)]taurine) using isolated hepatocytes and intact liver tissue. Photoaffinity labeling of isolated hepatocytes with [3H]-7,7-ASLCT on the one hand and with [3H]-7,7-ACT and [3H]-7,7-ALCT on the other resulted in a different labeling pattern of cytosolic polypeptides, without a relevant incorporation of radioactivity into subunits of glutathione transferases. This suggests that glutathione transferases play no role in the transport of dianionic or of monoanionic bile salts. With [3H]-7,7-ACT and [3H]-7,7-ALCT a moderate incorporation of radioactivity was found in polypeptides with apparent M(r)s of 33,000, 38,000, and 54,000, whereas with [3H]-7,7-ASLCT, a polypeptide with an apparent M(r) of 14,000, identified as H-FABP, was markedly and almost exclusively labeled. Photoaffinity labeling of specimens of intact liver tissue resulted in a labeling pattern of cytosolic polypeptides comparable to that obtained from photolabeled isolated hepatocytes. All results suggest that transcellular transport of dianionic sulfated as well as taurine-conjugated bile salts and of monoanionic taurine-conjugated bile salts follows different pathways. In intracellular transport of taurine-conjugated bile salts, several cytosolic polypeptides may have a function, whereas, in transport of taurine-conjugated 3 alpha-sulfato bile salts, only H-FABP appears to be involved.
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Base de dados:
MEDLINE
Assunto principal:
Ésteres do Ácido Sulfúrico
/
Taurina
/
Ácidos e Sais Biliares
/
Proteínas de Transporte
/
Proteína P2 de Mielina
/
Fígado
/
Proteínas de Neoplasias
/
Proteínas do Tecido Nervoso
Idioma:
En
Ano de publicação:
1995
Tipo de documento:
Article