Specific binding of the endocytosis tracer horseradish peroxidase to intestinal fatty acid-binding protein (I-FABP) in apical membranes of carp enterocytes
✍ Scribed by Concha, Margarita I. ;Santander, Cristi�n ;Villanueva, Julieta ;Amthauer, Rodolfo
- Publisher
- John Wiley and Sons
- Year
- 2002
- Tongue
- English
- Weight
- 400 KB
- Volume
- 293
- Category
- Article
- ISSN
- 0022-104X
No coin nor oath required. For personal study only.
✦ Synopsis
Abstract
In a previous study we had demonstrated that a 15‐kDa protein present in carp intestinal brush‐border membrane vesicles (BBMV) was able to bind the endocytosis tracer horseradish peroxidase (HRP) with high specificity. Here we show that this protein corresponds to a peripheral membrane protein, identified by partial amino acid sequence analysis as the intestinal fatty acid‐binding protein (I‐FABP), a member of the small cytosolic fatty acid binding protein family (FABPs). The presence of I‐FABP and its HRP‐binding activity was demonstrated both in the cytosolic and membrane‐associated fractions of intestinal mucosa by Western and ligand blot analyses, respectively. Also, both fractions displayed significant capacity to bind [^3^H]palmitic acid, a known ligand for I‐FABP. Immunohistochemical analysis showed that I‐FABP localizes both in the cytosol and in the brush‐border membranes of epithelial cells. Taken together the unusual extra‐cellular localization of I‐FABP as well as its ability to interact with HRP suggests a novel function for this protein in the intestinal mucosa. J. Exp. Zool. 293:541–550, 2002. © 2002 Wiley‐Liss, Inc.