Serum Proteins & Associated Disorders Flashcards
1
Q
alpha1-globulin class
A
- alpha1-antitrypsin
- alpha1-acid glycoproteins
- alpha-Fetoproteins
- Transcortin
- Retinol binding protein
2
Q
alpha2-globulin class
A
- haptoglobulin
- alpha2-macroglobulin
- ceruloplasmin
3
Q
Beta-globulins
A
- transferrin
- complement C3
4
Q
delta-globulins class
A
- All classes of Ig
5
Q
Compounds binding Albumin
A
- Bilirubin
- NEFA
- Ca2+
- Drugs
6
Q
alpha1-antitrypsin
A
- SER protease inhibitor
- aka anti-elastase
- 90% of alpha-globulin fraction
- Substition of Lys for Glu slows its secretion from hepatocytes
- results in excess elastase destruction of alveolar walls in lung tissue by digesting elastin fibres, leading emphysema
- Pt with alpha1ATD also at higher risk of developing cirrhosis & liver failure (defective alpha1AT fails to be excreted from hepatocytes)
- Smoking of tobacco also harmful b/c smoke oxidises Met-358 of alpha1-AT
7
Q
Alpha-Fetoprotein (AFP)
A
- w/in 12 mo, AFP almost totally replaced by albumin
- synthesized by foetal liver & found in amniotic fluid; high levels of AFP in amniotic fluid indicative of neural tube defects
- very low conc. in adults; very high levels indicative of hepatocell carcinomas
8
Q
Retinol-binding protein & transcortin
A
- transports retinol (form of Vit. A)
- Transcortin transports cortisol & cortisone
9
Q
Ceruloplasmin
A
- synthesized in liver containing 6 atoms of Cu in its structure
- carries 90% of plasma copper, remainder is transported by albumin
- Copper needs for:
- Tyrosinase
- Cytochrome oxidase
- SOD
- exhibits copper-dependent oxidase activity associated with oxidation of Fe2+ into Fe3+
- plays a critical role in recycling Fe2+ & Fe3+ enabling its binding to apotransferrin
Copper physiology
- Copper absorbed in gut
- Complexes with albumin in hepatic portal v., the majority of which taken up by liver
- binds to hepatic Ceruloplasmin & released into systemic circulation
- Senescent Ceruloplasmin undergoes lysosomal degradation and then biliary excretion
- excess copper excreted into bile via ATPase protein (ATB7B) which also facilitates binding of copper to Ceruloplasmin
10
Q
Haptoglobin
A
- synthesized primarily in liver (also in reticuloendothelial system to less extent)
- Scavenger binding protein
- Hb/haptoglobin complexes degraded by reticuloendothelial system; iron recycled
- also binds to insulin
Hemolytic anemia
- following intravascular hemolysis, Hb dissociates into alphabeta-dimers which are small enough to enter Glom Filtrate
- Haptoglobin binds alphabeta-dimers of Hb preventing Renal Excretion and loss of iron
- any free heme binds to hemopexin (another scavenger binding protein)
- serum haptoglobin levels fall in all hemolytic anemia
- does not bind to myoglobin released from myocytes and thus serum haptoglobin levels are nl with myopathies
11
Q
alpha2-Macroglobulin
A
- Protease inhibitors with broad specificity
- binds proteases that have leaked into blood from necrotic tissues eg. collagenase and those involved in blood clotting cascade (25% of thrombin inhibition)
12
Q
Transferrin
A
- acts as intracell storage of iron
- synthesized in liver
- each protein has 2 binding sites which can transport a Fe3+ primarily to bone marrow & liver
- almost all iron in plasma bound to transferrin
- protects against toxic (oxidising) effects of Fe3+
- transferrin receptors bind iron/transferrin complex but only Fe3+ assimilated. Transferrin then released & reused
*
13
Q
Hemopexin
A
- If Hb dissociates to heme & globin, hemopexin binds to free heme
- Heme/hemopexin complex is removed from circulation by the liver, where iron become bound to intracell ferritin thus scavenging & storing Fe3+
14
Q
Ig fx
A
- IgG: accounts for 75% of total Ig; binds antigenic proteins prior to phagocytosis
- IgA: primary defense mechanism protecting mucous membranes
- IgM: confined to intravascular space. 1st Ab to be produced following antigenic challenge
15
Q
Proteins of immune & inflammatory respones
A
During inflammation, acute phase proteins are synthesized including:
- C-Reactive Proteins (CRP, a beta-globulin)
- Protease inhibitors (alpha-macroglobulins)
- Scavengers suchas haptoglobulin & hemopexin
Complement system:
- synthesized by macrophages & hepatocytes
- involved in bacterial cell lysis, vasodilation, chemotaxis
