Retinol Binding Protein Essay

1667 words - 7 pages


Vitamin A, in its various forms, is an essential component of mammalian health. In addition to its well-documented role in vision, Vitamin A contributes to several other important biological functions including nuclear transcription, skin cell differentiation, growth, and immunity. As animals are not capable of synthesis, vitamin A and its metabolites (collectively know as the retinoids) must be obtained through the diet (Goodman 1984). Two major forms of vitamin A are found in food: retinol and carotenoids. All of these fat-soluble vitamins contain two distinct structural features that contribute to all of their activity. The first is a β-ionone ring to which the second critical motif, an isoprenoid chain, is attached.
Retinol, the major circulating form of vitamin A, is not biologically active. Rather, it serves as the metabolic precursor for the active retinoids (Chapman 2012). Oxidation at C-15 converts retinol to the visual pigment retinal, while subsequent oxidation of the aldehyde produces retinoic acid, which is involved in gene transcription (Figure 1). It is important for the body to maintain plasma retinol homeostasis to serve as a precursor reservoir for these active retinoids.
Mobilization of Vitamin A from the liver and its circulation to peripheral tissues is a highly regulated process. Delivery without appreciable loss of retinol requires it be bound tightly to plasma retinol-binding protein (RBP). RBP, first described by Goodman and colleagues in 1968, is synthesized in the endoplasmic reticulum of hepatocytes and contains a single binding site for only all-trans-retinol (Goodman 1980). Upon secretion into the plasma, Retinol-RBP circulates as a complex with a larger protein, transthyretin (TTR). As a tetramer, one TTR is capable of binding two molecules of retinol-binding protein and such binding prevents the loss of the low molecular weight RBP through glomerular filtration at the kidneys (Newcomer and Ong 2000). In the transport of vitamin A, retinol-binding protein provides a comprehensive study of protein-protein and protein-ligand interactions. This review outlines the structural features of plasma retinol-binding protein and relates them to the intermolecular interactions and functional role of this protein.

Structural Features of Retinol-Binding Protein

Retinol-binding protein is a member of the lipocalins, a family of extracellular proteins involved in the transport of small, hydrophobic molecules. RBP consists of 182 amino acid residues. The primary amino acid sequence and distribution of 3 disulfide bridges has been elucidated via cyanogen bromide (CNBr) fragmentation (Figure 2 and Figure 3). Primary structure ultimately determines the protein’s three-dimensional arrangement and RBP was the first lipocalin molecule for which X-ray structure was described. As such, serves as a “prototypic” reference for newly reported lipocalin structures (Newcomer 1984).

Up-and-down β-barrel

The most...

Find Another Essay On Retinol Binding Protein

Hamlet as Victim and Hero Essay

1301 words - 5 pages Hamlet as Victim and Hero      Hamlet, Prince of Denmark, a Shakespearean tragedy, tells the story of Prince Hamlet, who gained the knowledge of a terrible incident that his kingdom had suffered. Claudius, the king of Denmark and Hamlet's uncle, had killed his own brother, the king, who was also the father of Hamlet, and married his brother's widow. Hamlet suffered these traumas to a severe degree, and his only relief was to defeat his

Essay on Light and Dark in Antigone

1188 words - 5 pages Use of Light and Dark in Antigone   The "Golden Age" of Greece is noted for its many contributions to the creative world, especially in its development of the play. These performances strived to emphasize Greek morals, and were produced principally for this purpose. Antigone, by Sophocles, is typical. The moral focused on in Antigone is the conflict between physis (nature) and nomos (law), with physis ultimately presiding over nomos

charant Creon as the Main Character of Antigone

1231 words - 5 pages Creon as the Main Character of Antigone   Throughout the Greek play Antigone by Sophocles, there exists a dispute as to who should receive the designation of main character. Antigone, the daughter of the cursed King Oedipus, as well as Creon, stately king of Thebes, both appear as the key figures in this historic play. I believe that Creon, king of Thebes, should be considered the main character in this work of Greek theater. Three

Free Macbeth Essays: Sleep and Sleeplessness

525 words - 2 pages The Sleep and Sleeplessness Motif in Macbeth We have consciences that function to tell us the difference between right and wrong. If we have clear consciences, we usually possess the ability to sleep. But when our consciences are full of guilt, we experience a state of sleeplessness. In Macbeth, Shakespeare uses the sleep and sleeplessness motif to represent Macbeth's and Lady Macbeth's consciences and the effect Macbeth's conscience has on

Life Outside of Life in Hawthorne’s Wakefield

898 words - 4 pages Life Outside of Life in Hawthorne’s Wakefield   Efficacy lies at the heart of human desires for immortality. Characters throughout literature and art are depicted as wanting to step aside and see what their world would be like without their individual contributions. The literary classic A Christmas Carol and the more recent, but ageless, film It’s Wonderful Life both use outside influences (three ghosts and Clarence the Angel

Essay on Identity in Song of Solomon

2172 words - 9 pages Searching for Identity in Song of Solomon         Abstract: Whether Africans really fly or just escape a monumental burden, perhaps only through death, is a decision Toni Morrison has apparently left to her readers. Never the less, no matter what you believe, within Song of Solomon, the suggestion is, that in order to "fly" you must go back to the beginning, back to your roots. You must learn the "art" from the old messages.   O

The Character of Oedipus in Oedipus and The Infernal Machine

904 words - 4 pages The Character of Oedipus in Oedipus and The Infernal Machine    The stories of Oedipus, as told through Seneca's Oedipus and Cocteau's The Infernal Machine, contain both similarites and differences. Both authors portray the character of Oedipus as being obstinate, ignorant, and inquisitive. Yet Seneca and Cocteau differ on their interpretation of the motives that propelled these characteristics of Oedipus. Seneca portrays Oedipus as a

Okonkwo's Tragic Flaws in Chinua Achebe's Things Fall Apart

3121 words - 12 pages        An increasing amount of contemporary literature traces its origins back to the early works of Greece. For ages, humans have fascinated themselves with the impossible notion of perfection. Unrealistic expectations placed on those who were thought to be the noblest or most honorable individuals have repeatedly led to disappointment and frustration, either on the part of those particular individuals or those they influence. Classic

Sophocles' Antigone - Antigone Must Challenge Creon

889 words - 4 pages Antigone Must Challenge Creon in Antigone   In his "Funeral Oration" Pericles, Athens's leader in their war with other city-states, rallies the patriotism of his people by reminding them of the things they value. He encourages a sense of duty to Athens even to the point of self-sacrifice. He glorifies the free and democratic Athenian way of life and extravagantly praises those willing to die for it. In Antigone, Creon, Thebes's leader in

The Role of Women in Homer’s Iliad

796 words - 3 pages The Role of Women in Homer’s Iliad Homer’s Iliad is undoubtedly focused on its male characters: Achilles, primarily, but also Hector and Agamemnon. Nevertheless, it seems that the most crucial characters in the epic are female. Homer uses the characters of Thetis, Andromache, and Helen as a basis for comparison to the male characters. Homer wants his audience to see and understand the folly of his male characters in choosing war over peace

A Comparison of Butler's Life and Kindred

1915 words - 8 pages A Comparison of Butler's Life and Kindred   What lies in the mind of an author as he or she begins the long task of writing a fiction novel? This question can be answered if the author's life is studied and then compared to the work itself. Octavia E. Butler's life and her novel Kindred have remarkable comparisons. This essay will point out important events of Butler's life and how they link to the mentioned novel. Octavia Estelle

Similar Essays

Top Down Peptidomics Of Bodily Fluids Essay

1809 words - 8 pages , angiogenin I, collagen XVIII], 33% belong to complement factors (C3, C4A, C9, D), transport proteins (transthyretin, serotransferrin, retinol binding protein, transforming growth factor-binding protein, IGF-binding protein), enzymes and enzyme inhibitors (lysozyme, carboxypeptidase N, pancreatic trypsin inhibitor, cystatin C, plasminogen, α-2-antiplasmin, inter-α-trypsin, inhibitor complex component II, α-1-antitrypsin, hexokinase type II

Types Of Fat Soluble Vitamins Essay

1083 words - 5 pages , fat-soluble vitamins can be classified into four major categories: vitamin A, vitamin D, vitamin E and vitamin K (refer to Figure 1 in Appendix 1). The first type of fat-soluble vitamin is vitamin A. Vitamin A is a group of unsaturated nutritional organic compounds which includes retinol, retinal, retinoic acid, and several provitamins A carotenoids. According to Hickenbottom, Lemke, and Clifford (2002), the vitamin A is derived from beta

Reality And Illusion In Shakespeare's Hamlet Reality, Appearance And Deception

896 words - 4 pages Reality and Illusion in Hamlet   Shakespeare’s play, Hamlet, begins with the appearance of a ghost, an apparition, possibly a hallucination. Thus, from the beginning, Shakespeare presents the air of uncertainty, of the unnatural, which drives the action of the play and develops in the protagonist as a struggle to clarify what only seems to be absolute and what is actually reality. Hamlet's mind, therefore, becomes the central force of the

Sub Plots In Hamlet Essay

1118 words - 4 pages Sub-plots in Hamlet   There are many things that critics say make Hamlet a "Great Work," one of which is the way that Shakespeare masterfully incorporates so many sub-plots into the story, and ties them all into the main plot of Hamlet’s revenge of his father’s murder. By the end of Act I, not only is the main plot identified, but many other sub-plots are introduced. Among the sub-plots are trust in the Ghost of King Hamlet, Fortinbras, and