biology

Retinol-binding protein

Retinol-binding protein is a biology topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Retinol-binding protein rather than just read about it. In short: Retinol-binding proteins (RBP) are a family of proteins with diverse functions. They are carrier proteins that bind retinol.

Key takeaways

Retinol-binding protein belongs to biology; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Retinol-binding protein to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Retinol-binding protein from memory before moving on to harder problems.

Reference excerpt

Retinol-binding proteins (RBP) are a family of proteins with diverse functions. They are carrier proteins that bind retinol. Assessment of retinol-binding protein is used to determine visceral protein mass in health-related nutritional studies. Retinol and retinoic acid play crucial roles in the modulation of gene expression and overall development of an embryo. However, deficit or excess of either one of these substances can cause early embryo mortality or developmental malformations. Regulation of transport and metabolism of retinol necessary for a successful pregnancy is accomplished via RBP. Retinol-binding proteins have been identified within the uterus, embryo, and extraembryonic tissue of the bovine, ovine, and porcine, clearly indicating that RBP plays a role in proper retinol exposure to the embryo and successful transport at the maternal-fetal interface. Further research is necessary to determine the exact effects of poor RBP expression on pregnancy and threshold levels for said expression.

Genes Cellular: RBP1, RBP2, RBP5, RBP7 Interstitial: RBP3 Plasma: RBP4

RBP in pregnancy Retinol plays a crucial role in the growth and differentiation of various body tissues, and it has been previously characterized that embryos are extremely sensitive to alterations in retinol concentration that can lead to spontaneous abortion and malformations occurring during development. Within a mature animal, retinol is transported from the liver via the circulatory system while bound to RBP to the desired target tissue. RBP is also bound to a carrier protein, transthyretin. The process by which RBP releases retinol for cellular availability is still unknown and not concisely determined.

Sites of synthesis Traditionally, RBP is synthesized within the liver with secretion being dependent upon retinol concentrations. However, the concentrations levels do not appear to have an effect upon transcription of RBP messenger RNA (mRNA) which remains constant. Literature reveals that the bovine endometrium has also been identified as a location of RBP synthesis, as well as, the conceptus and extraembryonic tissues of various livestock species.

Types Plasma retinol-binding protein, the retinol transport vehicle in serum. CRBP I/II, cellular-binding proteins involved in transport of retinol and metabolites into retinyl esters for storage or into retinoic acid. CRABPs, cellular retinoic acid–binding proteins capable of binding retinol and retinoic acid with high affinity. It has also been characterized that CRABPs are involved in many aspects of the retinoic acid signaling pathway such as the regulation and availability of retinoic acid to nuclear receptors.

Presence in livestock species during gestation Bovine/Ovine RBP, identical to that found in plasma has been identified in the placental tissues of both the ovine and the bovine, suggesting that RBP may be highly involved in retinol transport and metabolism during pregnancy. However, exact timing of expression had been yet to be identified. An antiserum specific for bovine conceptus RBP and immunohistochemistry has been utilized to identify the presence of RBP at different stages of early pregnancy. Strong immunostaining and hybridization were observed in the trophectoderm of tubular, but not spherical blastocysts at day 13. RBP mRNA was localized to epithelial cells of the chorion, allantois, and amnion at day 45 of pregnancy. Lastly, RBP mRNA was detected in the cotyledons, the fetal contribution to the placenta and the site of attachment to the uterine epithelium for fetal/maternal exchange. Expression of RBP in developing conceptuses, extraembryonic membranes, and at the fetal-maternal interface indicate that there may be some regulation of retinol transport and metabolism that occurs due to RBP by the extraembryonic membranes. Within the uterus of pregnant bovines, it has been found that RBP synthesis in the luminal and glandular epithelium is quite similar to that of a cyclic animal's; however upon reaching day 17 of the estrous cycle, levels of RBP remain constant and continue to gradually rise throughout gestation. It has also been suggested that ovarian steroids may play a role in regulating uterine RBP expression.

Porcine All three previously mentioned types of retinol-binding proteins (RBP, CRBP, CRABP) have been identified within the porcine placenta during pregnancy via immunohistochemistry. As previously mentioned, retinol and retinoic acid are modulators of gene expression and are necessary for the proper development and growth of a conceptus. Porcine exhibit a diffuse type placenta that has areolar-gland subunits which allows for transport of larger molecules between dam and fetus. RBP and CRBP have been identified in the endometrial glands and areolar trophoblasts, suggesting that RBP is crucial in transport of retinol from the gland to the trophectoderm of the conceptus. RBP expression has also been identified within the yolk sac, myometrium, oviduct, and numerous other fetal tissues.

Illustrations

Worked examples

Example 1 — a first encounter with Retinol-binding protein

Start with the simplest possible case. Write down what Retinol-binding protein claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In biology, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Retinol-binding protein before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Retinol-binding protein ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Retinol-binding protein

In research: Retinol-binding protein appears in biology research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Retinol-binding protein in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Retinol-binding protein is common in secondary-school and first-year university syllabi. It links to neighbouring topics Peripheral membrane proteins, Proteins, so understanding it makes those chapters shorter.
In everyday life: Look for Retinol-binding protein outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study Retinol-binding protein in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Retinol-binding protein means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
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Frequently asked questions

What is Retinol-binding protein in simple terms?

Retinol-binding proteins (RBP) are a family of proteins with diverse functions. They are carrier proteins that bind retinol.

Why does Retinol-binding protein matter?

Because it connects several biology ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Retinol-binding protein?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Retinol-binding protein.