Sterols are crucial lipid components that regulate membrane permeability and fluidity and are the precursors of bioactive steroids. The plant sterols exist as three major forms, free sterols, steryl glycosides and steryl esters. The storage of steryl esters in lipid droplets has been shown to contribute to cellular sterol homeostasis. To further document cellular aspects of sterol biosynthesis ...

The relationship between sterol uptake and heme competence in two yeast strains impaired in heme synthesis, namely, G204 and H12-6A, was analyzed. To evaluate heme availability, a heterologous 17alpha-hydroxylase cytochrome P-450 cDNA (P-450c17) was expressed in these strains, and its activity was measured in vivo. Heme deficiency in G204 led to accumulation of squalene and lethality. The heter...

Scavenger receptor class B type I (SR-BI) is expressed in macrophages, but its role in sterol trafficking in these cells remains controversial. We examined the effect of sterol loading on SR-BI expression in human monocytes/macrophages, mouse peritoneal macrophages, and a cultured mouse macrophage cell line (J774 cells). Sterol loading using either acetylated LDL or 25-hydroxycholesterol result...

A series of LM cell variants resistant to filipin, but not auxotrophic for sterol, was isolated by plating mutagenized, filipin-treated cells on soft agar medium containing no sterol. Cloned variants were assayed for growth in the presence and absence of sterol or unsaturated fatty acid. Filipin-resistant clones whose growth rate was unaffected by the addition of sterol to the medium were furth...

The Niemann-Pick C1 (NPC1) protein is a key participant in intracellular sterol trafficking and regulation of cholesterol homeostasis. NPC1 contains a pentahelical region that is evolutionarily related to sterol-sensing domains found in other polytopic proteins involved in sterol interactions or sterol metabolism, including sterol regulatory element-binding protein cleavage-activating protein a...

The oomycete class includes pathogens of animals and plants which are responsible for some of the most significant global losses in agriculture and aquaculture. There is a need to replace traditional chemical means of controlling oomycete growth with more targeted approaches, and the inhibition of sterol synthesis is one promising area. To better direct these efforts, we have studied sterol acq...

BACKGROUND Sterols are vital structural and regulatory components in eukaryotic cells; however, their biosynthetic pathways and functional roles in microalgae remain poorly understood. RESULTS In the oleaginous microalga Nannochloropsis oceanica, the sterol biosynthetic pathway produces phytosterols as minor products and cholesterol as the major product. The evidence together with their deduc...

ABSTRACT: Iran is considered number one producer of pomegranate throughout the world. The oil extracted from pomegranate seed is considered to have great medical and nutritional values, therefore the study is concerned with this unique and valuable oil specially its chemical attributes. Five different varieties of pomegranate were obtained from Saveh Pomegranate Research Institute. The seeds we...

Structural properties of paeonol-encapsulated liposomes containing cholesterol or stigmasterol at 37°C have been investigated by synchrotron small-angle X-ray scattering (SAXS) and wide-angle X-ray scattering (WAXS) techniques. We compared the structural properties of pure dipalmitoylphosphatidylcholine (DPPC) liposomes, sterol–DPPC liposomes, and those of paeonol–sterol–DPPC liposomes at diffe...

In cultured human dermal microvessel endothelial cells, the rate of efflux (about twofold greater than for fibroblasts under equivalent conditions) was coupled to an equivalent high rate of sterol net transport from the cells to the medium. This net transport was linked with esterification via lecithin:cholesterol acyltransferase. Since the use of free sterol by plasma transferase is constant, ...