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Where are most of the plasma proteins synthesized?
Where are most of the plasma proteins synthesized?
Liver
What is the exception to the general rule of plasma protein synthesis in the liver?
What is the exception to the general rule of plasma protein synthesis in the liver?
Gamma globulins
What is the rationale behind synthesizing plasma proteins as preproproteins, which are immature forms?
What is the rationale behind synthesizing plasma proteins as preproproteins, which are immature forms?
To protect tissues synthesizing the proteins.
What is the difference between a preproprotein and a proprotein?
What is the difference between a preproprotein and a proprotein?
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Plasma proteins exhibit little variation in their half-lives.
Plasma proteins exhibit little variation in their half-lives.
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What is the half-life of albumin?
What is the half-life of albumin?
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What is the half-life of haptoglobin?
What is the half-life of haptoglobin?
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How can diseases affect the half-life of plasma proteins?
How can diseases affect the half-life of plasma proteins?
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What is the example given in the text regarding the impact of disease on plasma protein half-life?
What is the example given in the text regarding the impact of disease on plasma protein half-life?
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A mutation in a protein's gene sequence always renders the protein non-functional.
A mutation in a protein's gene sequence always renders the protein non-functional.
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A mutation that is passed down to offspring and spreads through generations will always become more common.
A mutation that is passed down to offspring and spreads through generations will always become more common.
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What is the term used to describe a mutation found in more than 1% of the population?
What is the term used to describe a mutation found in more than 1% of the population?
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Polymorphisms in plasma proteins are rare and only affect a few specific proteins.
Polymorphisms in plasma proteins are rare and only affect a few specific proteins.
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Polymorphism always causes a disease.
Polymorphism always causes a disease.
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What is an example of a polymorphism in plasma protein?
What is an example of a polymorphism in plasma protein?
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How many general functions of plasma proteins are mentioned in the text?
How many general functions of plasma proteins are mentioned in the text?
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What is the function of rennin in the context of plasma proteins?
What is the function of rennin in the context of plasma proteins?
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What is the specific function of immunoglobulins within plasma proteins?
What is the specific function of immunoglobulins within plasma proteins?
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Which plasma protein plays a role in hormonal function?
Which plasma protein plays a role in hormonal function?
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List three examples of transport proteins mentioned in the text.
List three examples of transport proteins mentioned in the text.
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What are Starling forces?
What are Starling forces?
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What are the two main forces that contribute to Starling forces?
What are the two main forces that contribute to Starling forces?
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What is the primary function of hydrostatic pressure in Starling forces?
What is the primary function of hydrostatic pressure in Starling forces?
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What is the primary function of oncotic pressure in Starling forces?
What is the primary function of oncotic pressure in Starling forces?
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The net hydrostatic pressure is higher at the venous end of the capillary compared to the arterial end.
The net hydrostatic pressure is higher at the venous end of the capillary compared to the arterial end.
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What is the outcome if the difference between the fluid leaving and returning at the capillary is within the range of 1-2 mmHg?
What is the outcome if the difference between the fluid leaving and returning at the capillary is within the range of 1-2 mmHg?
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What condition arises when the difference between fluid leaving and returning at the capillary exceeds 1-2 mmHg, potentially leading to fluid accumulation in tissues?
What condition arises when the difference between fluid leaving and returning at the capillary exceeds 1-2 mmHg, potentially leading to fluid accumulation in tissues?
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What are acute-phase proteins?
What are acute-phase proteins?
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Acute-phase proteins typically decrease in concentration in response to inflammatory processes.
Acute-phase proteins typically decrease in concentration in response to inflammatory processes.
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What cytokine is mentioned in the text as a trigger for the activation of acute-phase proteins?
What cytokine is mentioned in the text as a trigger for the activation of acute-phase proteins?
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What intracellular factor is activated by IL-1, leading to the production of acute-phase proteins?
What intracellular factor is activated by IL-1, leading to the production of acute-phase proteins?
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Where does NF-kB translocate to after activation, initiating the production of acute-phase proteins?
Where does NF-kB translocate to after activation, initiating the production of acute-phase proteins?
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What are the four examples of positive acute-phase proteins mentioned in the text?
What are the four examples of positive acute-phase proteins mentioned in the text?
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What is the primary reason why some proteins are classified as negative acute-phase proteins?
What is the primary reason why some proteins are classified as negative acute-phase proteins?
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What are the three examples of negative acute-phase proteins mentioned in the text?
What are the three examples of negative acute-phase proteins mentioned in the text?
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What is the size of albumin?
What is the size of albumin?
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Albumin is synthesized in a directly active form.
Albumin is synthesized in a directly active form.
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Albumin is a multimeric protein, composed of multiple polypeptide chains.
Albumin is a multimeric protein, composed of multiple polypeptide chains.
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How many disulfide bonds are present in albumin to maintain its structure?
How many disulfide bonds are present in albumin to maintain its structure?
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What type of charge does albumin carry?
What type of charge does albumin carry?
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Albumin's ellipsoidal (oval) shape reduces its surface area.
Albumin's ellipsoidal (oval) shape reduces its surface area.
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Albumin is predominantly acidic at pH 7.4.
Albumin is predominantly acidic at pH 7.4.
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What is the primary contributor to osmotic pressure in the blood?
What is the primary contributor to osmotic pressure in the blood?
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What percentage of total protein synthesis is attributed to albumin synthesis in the liver?
What percentage of total protein synthesis is attributed to albumin synthesis in the liver?
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Why are albumin levels used in liver function tests?
Why are albumin levels used in liver function tests?
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The long half-life of albumin enhances its accuracy in assessing short-term liver function changes.
The long half-life of albumin enhances its accuracy in assessing short-term liver function changes.
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What is the main function of albumin in the body?
What is the main function of albumin in the body?
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Albumin is known to bind to heavy metals but not drugs.
Albumin is known to bind to heavy metals but not drugs.
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What is the potential consequence of two drugs binding to the same site on albumin?
What is the potential consequence of two drugs binding to the same site on albumin?
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What are the two forms in which drugs can exist in the body?
What are the two forms in which drugs can exist in the body?
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What is the condition characterized by the absence of albumin in the blood?
What is the condition characterized by the absence of albumin in the blood?
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Analbuminemia is a fatal condition.
Analbuminemia is a fatal condition.
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What is the condition characterized by a decrease in albumin levels in the blood?
What is the condition characterized by a decrease in albumin levels in the blood?
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Hypoalbuminemia always leads to edema in the abdomen.
Hypoalbuminemia always leads to edema in the abdomen.
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What condition arises when bilirubin accumulates in the brain cells?
What condition arises when bilirubin accumulates in the brain cells?
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Why is aspirin contraindicated in newborns?
Why is aspirin contraindicated in newborns?
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Warfarin, phenytoin, and dicoumarol are all anticoagulants.
Warfarin, phenytoin, and dicoumarol are all anticoagulants.
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Why should phenytoin and dicoumarol not be administered together?
Why should phenytoin and dicoumarol not be administered together?
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Study Notes
Biochemistry - Plasma Proteins
- Plasma proteins, primarily albumin and globulins, are synthesized in the liver. An exception are gamma globulins, immunoglobulins produced by mature B lymphocytes found in bone marrow, spleen, and lymph nodes.
- Plasma proteins are initially synthesized as preproproteins (immature forms).
- Preproproteins are protected within the synthesizing tissues in an inactive state, ready for activation as needed. This prevents harmful effects on the cell where they are produced.
- Preproproteins require two processing steps to mature, while proteins needing just one step are called proproteins.
- Post-translational modifications occur affecting the synthesis time, from 30 minutes to hours, and involve glycoprotein formations (N- or O-linked) with exceptions for albumin.
- Plasma proteins exhibit polymorphism and varying half-lives, influenced by type and function, and binding with other molecules.
- Half-life is determined through isotope labeling studies (e.g., using I-131).
- Albumin has a half-life of approximately 20 days, while haptoglobin's is around 5 days.
- Diseases can affect protein half-lives, such as protein-losing gastroenteropathy where proteins are lost due to the GI tract becoming more separated. This can be seen in Crohn's disease where albumin's half-life can decrease by one day.
- Mutations in a protein's gene sequence (polymorphism) can slightly alter or enhance the protein's function or have no effect. If a mutation is passed on and becomes common (more than 1% of the population), it's considered polymorphism. This affects multiple plasma proteins like alpha-1-antitrypsin, haptoglobin, transferrin, ceruplasmin, and immunoglobulins. ABO blood grouping is a well-known example.
- Polymorphism does not always lead to disease. It can be a Mendelian/monogenic trait or exist in populations with at least two distinct phenotypes.
General and Specific Functions of Plasma Proteins
- All plasma proteins generally have nutritive roles (providing energy source),
- Maintain blood pH (buffering capacity),
- Contribute to blood viscosity (thickness),
- Maintain blood osmotic pressure.
- Specific protein functions vary. Some are enzymes (e.g., rennin, blood clotting factors, lipases), involved in humoral immunity (immunoglobulins), blood clotting (coagulation factors), hormones (e.g., erythropoietin), and transport proteins (e.g., transferrin, thyroxine-binding globulin).
Starling Forces
- Proteins are confined to the blood vessels and prevent water loss.
- Blood pressure pushes water out of the vessels, opposing the force exerted by plasma proteins holding water inside the vessels.
- Hydrostatic pressure at an arterial capillary ending is 40 mmHg, opposed by an oncotic pressure of 25 mmHg, resulting in a net pressure of 15 mmHg going from the capillary to the tissues.
- At the venous capillary end, hydrostatic pressure is 10 mmHg and oncotic pressure is still 25 mmHg resulting in a net pressure of 15 mmHg from the tissues towards the capillary.
- Fluid and waste are returned to blood vessels with minimal changes.
- If the difference between water entering and leaving the capillaries is 1-2 mmHg it is unlikely to cause issues. If it is greater it leads to fluid buildup and edema.
Acute-Phase Proteins
- Acute-phase proteins dramatically increase in response to tissue damage, chronic inflammation, and cancer.
- Examples of positive acute-phase proteins include C-reactive protein (CRP), alpha 1-antitrypsin, haptoglobin, and fibrinogen. Increased concentration of these proteins during inflammation.
- Conversely, negative acute-phase proteins (like pre-albumin, albumin, and transferrin) may decrease during an inflammatory response. The body uses these adjustments to maintain the overall balance of plasma proteins
Albumin
- Albumin is a major plasma protein. It's a preproprotein that undergoes several post-translational modifications before becoming functional, forming three polypeptide domains (1A&1B, 2A&2B, and 3A&3B). It is a monomeric protein composed of 585 amino acids held together by 17 disulfide bonds
- Albumin is highly negatively charged (approximately 20 negative charges). This helps maintain an oval shape and a large surface area to perform diverse functions. Albumin is important for the transport of various molecules in the bloodstream including free fatty acids, steroid hormones, bilirubin (a breakdown product of heme which causes jaundice), tryptophan, and various metals.
- Albumin is primarily responsible for the osmotic pressure in blood. About 75-80% of the osmotic pressure in the blood depends on the presence and concentration of albumin.
- Albumin has a half-life of ~20 days, so levels reflect longer-term changes in liver function.
- Drug-drug interactions can occur as drugs might compete for albumin-binding sites, altering the effectiveness of one or more drugs.
- An abnormal absence of albumin (analbuminemia) is a rare autosomal recessive genetic disorder.
Clinical Disorders
- Hypoalbuminemia is a decrease in blood albumin levels (less than 2 g/dL), which may be linked to liver issues or other conditions causing edema.
- Hyperalbuminemia is an increase in blood albumin levels, which can occur due to dehydration or some cancers.
- Bilirubin toxicity can occur if bilirubin and drugs compete for albumin-binding sites in the blood, leading to increased levels of bilirubin in the plasma and causing jaundice in newborns.
- Interactions between certain drugs (like phenytoin and dicoumarol) can exist and possibly alter their effectiveness due to competition for binding sites.
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Description
Explore the fascinating world of plasma proteins, primarily focusing on albumin and globulins, their synthesis in the liver, and the various stages of maturation. This quiz covers aspects of preproproteins, post-translational modifications, and the impact of factors such as half-life and binding variations. Test your knowledge on how these proteins function and their significance in biological systems.
