Sterol carrier protein 2 and fatty acid-binding protein. Separate and distinct physiological functions.
J Biol Chem
; 260(8): 4733-9, 1985 Apr 25.
Article
en En
| MEDLINE
| ID: mdl-3921536
ABSTRACT
Sterol carrier protein 2 (SCP-2) participates in the microsomal conversion of lanosterol to cholesterol, in the conversion of cholesterol to cholesterol ester, and in intracellular cholesterol transfers. The stoichiometry of binding between cholesterol and SCP-2 is 11. However, reports have appeared attributing sterol carrier protein activity to a protein preparation identical to hepatic fatty acid-binding protein (FABP). Therefore, the present investigation was conducted to compare homogeneous preparations of FABP and SCP-2 with respect to their capacities to participate as carrier proteins in reactions involving sterols or fatty acids. The results show that SCP-2 and FABP have separate and distinct physiological functions, with SCP-2 participating in reactions involving sterols and FABP participating in reactions involving fatty acid binding and/or transport. Furthermore, there is no overlap in substrate specificities, i.e. FABP does not possess sterol carrier protein activity and SCP-2 does not specifically bind or transport fatty acid. As long as only small quantities of organic solvent (1.6 volume %) were used for substrate addition, the sterol delta 7-reductase liver microsomal assay for SCP-2 correlated well with the physiologically relevant assays employed in the reconstituted adrenal system. The sterol carrier protein activity previously attributed to rat hepatic FABP is explained by the presence of significant quantities of propylene glycol (15 volume %) or Tween 80 in the assay procedure.
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Colección:
01-internacional
Base de datos:
MEDLINE
Asunto principal:
Proteínas de Plantas
/
Proteínas Portadoras
/
Oxidorreductasas actuantes sobre Donantes de Grupo CH-CH
/
Proteínas de Neoplasias
/
Proteínas del Tejido Nervioso
Límite:
Animals
Idioma:
En
Revista:
J Biol Chem
Año:
1985
Tipo del documento:
Article