Spodoptera frugiperda retinol dehydratase catalyzes the conversion of retinol to the retro-retinoid anhydroretinol. It shares sequence homology with the family of mammalian cytosolic sulfotransferases and provides the first link between sulfotransferases and retinol metabolism. In this study the enzymatic properties of retinol dehydratase were examined using bacterially expressed protein. We sh...

Tissue uptake and distribution of retinol from circulatory vitamin A transport complex was studied in order to determine the origin of the increased serum retinol in rats with short-term acute renal failure. In rats with acute renal failure, serum retinol increased 37-70% within 2 h after surgery. After an injection of donor plasma containing 1.8 muCi of [3H]retinol in retinol transport complex...

Retinoids have been shown to enhance developmental competence of the oocyte in cattle, sheep and pigs. In this study we investigated whether exogenous retinol stimulates the bovine oocyte during its intrafollicular growth and the time limits of exposure to exogenous retinol. In addition, we also determined the efficiency of ovum pick-up techniques in combination with retinol treatment and the v...

Retinol-binding protein (RBP) is the sole specific transport protein for retinol (vitamin A) in the circulation, and its single known function is to deliver retinol to tissues. Within tissues, retinol is activated to retinoic acid, which binds to nuclear receptors to regulate transcription of >300 diverse target genes. In the eye, retinol is also activated to 11-cis-retinal, the visual chromoph...

Studies were conducted to explore in rats the role of retinol in the regulation of the synthesis and secretion of retinol-binding protein (RBP) by the visceral yolk sac compared to the liver. Previous studies have shown that in retinol deficiency, hepatic RBP secretion is specifically inhibited, whereas hepatic RBP synthesis rate is unchanged. Retinol-depleted, retinoic acid-supplemented female...

BACKGROUND Vitamin A (retinol), which is required for normal fetal development and successful gestation, circulates in the blood bound to a specific protein, the retinol binding protein (RBP). Little is known about the transport and metabolism of this complex protein or about retinol status during normal human pregnancy. OBJECTIVE The aim of this study was to assess retinol status and transpo...

The influence of extracellular fatty acids on the uptake and esterification of [3H]retinol bound to human retinol-binding protein (RBP), to RBP-transthyretin (TTR), or in dispersed form by the human hepatoma, HepG2, and human mammary epithelial carcinoma, MCF-7, cell lines was studied. The esterification of [3H]retinol was significantly increased in cells incubated with myristic, palmitic, stea...

The stellate cells of the liver are the main storage site of retinyl esters in the body. During cultivation in vitro of stellate cells isolated from rat and rabbit livers were observed that the cells rapidly loose their retinyl ester content. Freshly isolated stellate cells contain about 144 nmol of total retinol/mg of protein, while cells cultivated for 14 days contained below 0.1 nmol/mg of p...

Retinol acetate hydrolase is localized in rat liver microsomes whereas the retinol palmitate-hydrolyzing activity was found in the nuclear and in the mitochondrial lysosome-rich fractions. Acetone-dried powder from whole rat liver retained all of its retinol palmitate-hydrolyzing activity. Ammonium sulfate fractionation of the acetone-dried powder yielded a partially purified enzyme liberating ...

Retinol plays a vital role in the immune response to infection, yet proteins that mediate retinol transport during infection have not been identified. Serum amyloid A (SAA) proteins are strongly induced in the liver by systemic infection and in the intestine by bacterial colonization, but their exact functions remain unclear. Here we show that mouse and human SAAs are retinol binding proteins. ...