The fatty acid-binding proteins (FABPs) are among the most abundant cytoplasmic constituents of
parenchymal cells . These small cytosolic proteins enhance the intracellular transport and
metabolism of fatty acids and may show an affinity for other ligands, such as retinoic acid, bile acids,
or prostaglandins. Different genes encode at least eight types of FABPs, which differ in their
specific binding properties and have each been named after the tissue of major occurrence.
NCBI Summary:
The intracellular fatty acid-binding proteins (FABPs) belong to a multigene family with nearly twenty identified members. FABPs are divided into at least three distinct types, namely the hepatic-, intestinal- and cardiac-type. They form 14-15 kDa proteins and are thought to participate in the uptake, intracellular metabolism and/or transport of long-chain fatty acids. They may also be responsible in the modulation of cell growth and proliferation. Intestinal fatty acid-binding protein 2 gene contains four exons and is an abundant cytosolic protein in small intestine epithelial cells. This gene has a polymorphism at codon 54 that identified an alanine-encoding allele and a threonine-encoding allele. Thr-54 protein is associated with increased fat oxidation and insulin resistance.
General function
Intracellular signaling cascade
Comment
Cellular localization
Cytoplasmic
Comment
Ovarian function
Steroid metabolism
Comment
Chandra P. Leo, et al 2001 used
DNA array to analyze changes in preovulatory gene expression in the rat
Ovary. They reported that
the
screening identified a group of candidate genes whose ovarian
expression and gonadotropin regulation was hitherto unknown. The
induction of three of these genes, encoding cutaneous fatty acid-binding
protein, the interleukin-4 receptor alpha chain, and prepronociceptin, was
confirmed and further characterized by Northern blot analysis. In addition,
in situ hybridization analysis showed that hCG administration resulted in
exclusive or predominant expression of all three genes in theca cells.
By contrast, the message for heart FABP was the most highly repressed message
among the 597 genes represented in the array.
Three other genes for FABPs-intestinal FABP, adipocyte FABP, and liver
FABP-were also represented on the array, but the quantification revealed no clear regulation of
the mRNA by hCG.
Iseki S, et al reported immunohistochemical localization of two types of fatty
acid-binding proteins in rat ovaries during postnatal development
and in immature rat ovaries treated with gonadotropins.
The ovary of adult rats expresses two types of cytoplasmic fatty
acid binding proteins (FABP), i.e., heart FABP (H-FABP) and intestinal 15 kDa
protein (I-15P). The immunoreactivity for H-FABP
occurred temporarily in the follicular epithelial (granulosa) cells from 3 days to 2
weeks post partum, and then was localized exclusively to the theca/interstitial
gland cells from 2 weeks to adulthood. In contrast, the immunoreactivity for I-15P
appeared temporarily in a small subset of theca/interstitial gland cells from 2 to 3
weeks, disappeared at 4 weeks, and was localized exclusively to the corpus
luteum cells after the onset of ovulation in the animal around 5 weeks. In the
immature rat ovaries induced to ovulate by treatment with gonadotropins,
I-15P-immunoreactive cells were first recognized in the luteinized granulosa layer
of large preovulatory follicles, and increased in number progressively in the
developing corpora lutea after the ovulation. These results suggest that FABPs play specific roles
in the ovarian hormone synthesis