Effect of Bilayer Phospholipid Composition and Curvature on Ligand Transfer by the α‐Tocopherol Transfer Protein

Zhang, Wen Xiao; Frahm, Grant E.; Morley, Samantha; Manor, Danny; Atkinson, Jeffrey

doi:10.1007/s11745-009-3310-x

Cited by 24 publications

(28 citation statements)

References 88 publications

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“…The α-TTP/ α-TOH complex moves to the plasma membrane where it is targeted by phosphatidylinositol bisphosphates (PIP2), which are essential interaction partners of α-TTP [76] . In this case, α-TTP has been shown to transfer α-TOH between membranes through direct proteinmembrane interactions [111][112][113] . In brief, experiments with liposomes have revealed that α-TTP acts as an α-TOH/ PIP2 exchanger [76] .…”

Section: Intracellular Binding Proteins α -Tocopherol Transfer Proteinmentioning

confidence: 99%

Complexity of vitamin E metabolism

Schmölz¹,

Birringer²,

Lorkowski³

et al. 2016

WJBC

176

138

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Bioavailability of vitamin E is influenced by several factors, most are highlighted in this review. While gender, age and genetic constitution influence vitamin E bioavailability but cannot be modified, life-style and intake of vitamin E can be. Numerous factors must be taken into account however, i.e. , when vitamin E is orally administrated, the food matrix may contain competing nutrients. The complex metabolic processes comprise intestinal absorption, vascular transport, hepatic sorting by intracellular binding proteins, such as the significant α-tocopherol-transfer protein, and hepatic metabolism. The coordinated changes involved in the hepatic metabolism of vitamin E provide an effective physiological pathway to protect tissues against the excessive accumulation of, in particular, non-α-tocopherol forms. Metabolism of vitamin E begins with one cycle of CYP4F2/CYP3A4-dependent ω-hydroxylation followed by five cycles of subsequent β-oxidation, and forms the water-soluble end-product carboxyethylhydroxychroman. All known hepatic metabolites can be conjugated and are excreted, depending on the length of their sidechain, either via urine or feces. The physiological handling of vitamin E underlies kinetics which vary between the different vitamin E forms. Here, saturation of the side-chain and also substitution of the chromanol ring system are important. Most of the metabolic reactions and processes that are involved with vitamin E are also shared by other fat soluble vitamins. Influencing interactions with other nutrients such as vitamin K or pharmaceuticals are also covered by this review. All these processes modulate the formation of vitamin E metabolites and their concentrations in tissues and body fluids. Differences in metabolism might be responsible for the discrepancies that have been observed in studies performed in vivo and in vitro using vitamin E as a REVIEW

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Section: Intracellular Binding Proteins α -Tocopherol Transfer Proteinmentioning

confidence: 99%

Complexity of vitamin E metabolism

Schmölz¹,

Birringer²,

Lorkowski³

et al. 2016

WJBC

176

138

View full text Add to dashboard Cite

show abstract

“…Hypothetically, this ␣ -tocopherol transfer function is necessary for the observed mechanism that enriches the plasma with ␣ -tocopherol, not with the other non-␣ -tocopherol ( 43,60,61 ). Notably, the liver ( 62 ), not the intestine, expresses ␣ -TTP; thus, liver, not the intestine, specifi cally discriminates between forms of vitamin E. The means by which ␣ -TTP facilitates ␣ -tocopherol secretion into plasma is unknown, but it is under investigation (63)(64)(65)(66)(67)(68)(69)(70). The current consensus is that syndromes ( 23 ), if the vitamin E is given as a stable micellar form ( 24 ).…”

Section: Hepatic Secretion Of ␣ -Tocopherol Into Plasmamentioning

confidence: 99%

Mechanisms for the prevention of vitamin E excess

Traber

2013

Journal of Lipid Research

116

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“…The hope is that a-tocohexaenol will be able to be used in a similar fashion as cis-parinaric acid, but be able to report more specifically on the location of tocopherol in a membrane. Other fluorescent analogues of tocopherol including C9-NBD-a-tocopherol [87] and C8-BODIPY-a-tocopherol (West, R., submitted) have been useful in determining the cellular location and transfer of tocopherol [88][89][90][91][92], but do not change fluorescence on oxidation.…”

Section: Do We Know Where Tocopherol Does Its Most Important Job?mentioning

confidence: 99%

The location and behavior of α‐tocopherol in membranes

Atkinson

Harroun

Wassall

et al. 2010

Molecular Nutrition Food Res

Self Cite

172

128

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Vitamin E (a-tocopherol) has long been recognized as the major antioxidant in biological membranes, and yet many structurally related questions persist of how the vitamin functions. For example, the very low levels of a-tocopherol reported for whole cell extracts question how this molecule can successfully protect the comparatively enormous quantities of PUFAcontaining phospholipids found in membranes that are highly susceptible to oxidative attack. The contemporary realization that membranes laterally segregate into regions of distinct lipid composition (domains), we propose, provides the answer. We hypothesize a-tocopherol partitions into domains that are enriched in polyunsaturated phospholipids, amplifying the concentration of the vitamin in the place where it is most needed. These highly disordered domains depleted in cholesterol are analogous, but organizationally antithetical, to the wellstudied lipid rafts. We review here the ideas that led to our hypothesis. Experimental evidence in support of the formation of PUFA-rich domains in model membranes is presented, focusing upon docosahexaenoic acid that is the most unsaturated fatty acid commonly found. Physical methodologies are then described to elucidate the nature of the interaction of a-tocopherol with PUFA and to establish that the vitamin and PUFA-containing phospholipids co-localize in non-raft domains.

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Effect of Bilayer Phospholipid Composition and Curvature on Ligand Transfer by the α‐Tocopherol Transfer Protein

Cited by 24 publications

References 88 publications

Complexity of vitamin E metabolism

Complexity of vitamin E metabolism

Mechanisms for the prevention of vitamin E excess

The location and behavior of α‐tocopherol in membranes

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