Special Topics Flashcards
Most common method of analyzing plasma proteins
Electrophoresis
Plasma Protein Quiz!
- Binds heme
- Binds extracorpuscular Hg
- Binds cortisol
- Forms a complex with retinol-binding protein and binds T4
- Hemopexin
- Haptoglobin
- Transcortin
- Tranthyretin
The following are examples of acute phase reactants.
- a1-antitrypsin
- haptoglobin
- a1-acid glycoprotein (orosomucoid)
- fibrinogen
- C-reactive protein
Transcription factor involved in the stimulation of synthesis of acute phase proteins
Nuclear factor kappa B
Released by mononuclear phagocytic cells - the PRINCIPAL - stimular of synthesis of acute phase reactants
IL-1
Albumin is the major protein of plasma making up ___ of total protein.
60%
This protein prevent loss of free hemoglobin into the kidney; conserving Fe present in Hg
Haptoglobin
Haptoglobin is decreased in ___ and increased in ___.
Decreased levels in hemolytic anemia. Hemolysis increases free Hg levels (Hg-Hp complex has a short half life of 90 mins vs 5 days for normal halptoglobin.
Increased level seen in chronic inflammatory states (haptoglobin is an acute phase reactant)
Site of absorption of Fe
Proximal duodenum
Name the proteins important in Fe metabolism.
- Incoming iron in Fe3+ state is reduced to Fe2+.
- Carries Fe in serum in the Fe3+ form
- Downregulates intestinal absorption and release of iron from macrophages
- Transports iron across the apical surface
- Transports iron across the basolateral surface
- Converts Fe2+ back to Fe3+ at the basolateral surface
- Protein which stores Fe in cells
- Ferrireductase
- Transferrin
- Hepcidin
- Divalent metal transporter 1
- Ferroportin
- Hephaestin
- Ferritin
If Fe levels are sufficient, levels of this protein increase to prevent further absorption of Fe.
Hepcidin
Major component of the a1 fraction of human plasma
a1-antitrypsin (a1-antiproteinase)
A1-antitrypsin is an example of a ___
Serine protease inhibitor
Group of small proteins in the cytosol of liver, kidney, and intestine; with a high content of cysteine and bind Cu, Zn, Cd and Hg
Metallothioneins
This plasma protein is synthesized by monocytes, hepatocytes, and astrocytes, inhibits many proteinases and directs many cytokines towards tissues or cells.
a2-macroglobulin
Amyloidosis quiz.
- Increased in multiple myeloma
- Increased in patients on chronic dialysis
- Mutant forms exist in familal amyloidotic neuropathies
- Alzheimer’s disease
- Ig light chain
- B2-microglobulin
- Transthyretin
- Amyloid B protein
Cleavage of immunoglobulin with ___ produces two antigen-binding fragments and one crystallizable fragment
Papain
Immunoglobulin Quiz!
- Lowest concentration in plasma
- Exists as dimer and may contain a J chain
- The antigen receptor on B cell
- Opsonization
- Complement fixation
- IgE
- IgM or IgA
- IgM
- IgG
- IgG or IgM
Which two monosaccharides are ACTIVELY transported across the small intestine?
Glucose
Galactose
Secondary active transport (via SGLT1)
The major lipids in the diet
Triacylglycerol
How does one differentiate lingual/gastric lipases from pancreatic lipases as to its action on TAGs?
Lingual/gastric lipases act on the sn-3 ester bond, forming 1,2-DAGs and free fatty acids.
Pancreatic lipase is specific for the ester links in positions 1 and 3 forming 2-MAG.
What is the monoacylglycerol pathway?
In the intestinal cells,
MAGs are hydrolyzes into glycerol and FFA
DAGs are re-acylated to TAGs
How are long-chain FAs different from medium-chain/short-chain FAs different in terms of its absorption?
Long chain FAs packaged into chylomicrons which enter lymphatics and thoracic duct.
Medium/short chain FA exist as FFAs and pass into the hepatic portal vein.
How are proteolytic enzymes which are secreted as zymogens activated?
Enteropeptidase is secreted by duodenal epithelial cells to activate trypsinogen.
Trypsin activates chymotrypsinogen, proelastase, procarboxypeptidase and aminopeptidase.
How is Vitamin D able to increase Ca absorption
It increases synthesis of the intracellular calcium binding protein CALBINDIN.
This compound in cereal and unleavened whole-wheat products chelate Ca and Zn causing deficiency.
Phytic acid
Phytase in yeast renders it inactive
How can fat malabsorption cause Ca deficiency?
Fat in the intestinal lumen form insoluble Ca salts.
You know that Vitamin C increases absorption of Fe. How?
Vitamin C is a reducing agent, reduces Fe3+ to Fe2+, which is the form absorbed by the enterocyte.
What is the effect of the following on Fe absorption?
- Alcohol
- Ca
- Fructose
- Increase
- Decrease
- Increase
Energy expenditure per L of O2 consumed
20 kJ
Differentiate cachexia from marasmus.
In marasmus, protein synthesis is reduced but catabolism is unaffected.
In cachexia, protein catabolism is increased.
Discuss three metabolic changes in cachexia.
- Tumor releases lactate, which is recycled into glucose (consumes 6ATP/glucose recycled)
- Stimulation of uncoupling proteins, leading to thermogenesis and oxidation of fuels
- Futile cycling of lipids (hormone sensitive lipase activated; FFAs produced are re-esterified at ATP cost).
Very commonly, a ___ precipitates Kwashiorkor.
Infection
Nutritional studies show that the average daily requirement for N is ___.
0.6 g/kg body weight
2 amino acids are synthesized in the body but only from essential amino acids.
Cysteine (from Methionine)
Tyrosine (from Phenylalanine)
Most frequent post-translational modification of proteins
Glycosylation (>50% have CHO moieties attached)
Mucin contains repeating amino acid sequences rich in:
Serine
Threonine
Proline
Mucins exhibit high content of O-glycan chains
What is the major class of glycoproteins? It is characterized by ___.
N-linked glycoproteins
Asn-GlcNAc linkage
(Other classes are O-linked glycoproteins and GPI-linked)
Common pentasaccharide found in N-linked glycoproteins
Man3 GlcNAc2
The formation of N-linked oligosaccharides is unique because it involves
Dolichol-P-P-oligosaccharide
Addition of this molecule causes enzymes to be marked for lysosomes. This is synthesized by which enzyme, deficient in which condition.
GlcNAc-1-P
GlcNAc phosphotransferase
I-Cell disease
Thick transparent, non-cellular envelope surrounding the oocyte
Zona pellucida
This O-linked glycoprotein functions as a receptor for the sperm
ZP3.
Interacts with galactosyl transferase on sperm; when activated, sperm releases proteases and hyaluronidase (acrosomal reaction)
What is the test used to diagnose PNH?
Ham’s Test.
Red cells much more sensitive to hemolysis in normal serum acidified to pH of 6.2
Explain the glycoprotein abnormality in RA.
Alteration in glycosylation of circulating Ig; lacking glactose in Fc and terminating in GlcNAc. Mannose-binding protein binds agalactosyl IgG and activates complement system contributing to chronic inflammation in joints.
Binds mannose, GlcNAc and other sugars in bacteria, fungi and viruses marking them for opsonization and destruction by complement.
Mannose binding protein
Influenza A binds to cell surface receptor molecules containing ___ via ___. Another enzyme allows it to elute newly synthesized progeny from host cells.
NeuAc via hemagglutinin
Neuraminidase
HIV-1 uses two glycoproteins.
- Attach to cell
- Fuse with host membrane
- gp120
2. gp41 (Fourty-one Fuses)
Helicobacter pylori attaches to two glycans on the epithelial cells.
Adhesin in the tail of H pylori interact with:
Neuraminyl-galactose
Lewis-B substance
___ of chilled platelets has been found to prevent clustering thereby prolonging its life.
Enzymic galactosylation
Major cross-links that form in elastin
Desmosine
Condensation of 3 Lys-derived aldehydes with an unmodified lysine
This glycoprotein is secreted into the ECM by fibroblasts and incorporated into structures that serve as scaffold for deposition of elastin.
Fibrillin
Zonular fiber = ectopia lentis
Periosteum = tall, arachnodactyly
Aorta = aortic aneurysm
A major glycoprotein of ECM with domains than binds heparin, fibrin, collagen, DNA and cell surfaces.
Fibronectin
Fibronectin contains an ___ sequence that binds to the receptor.
RGD
Arginine - Glycine - Aspartic acid
The basement membrane in the nephron has three protein components and 2 GAGs
Proteins
- Type 4 collagen
- Laminin
- Entactin
GAG
- Heparin
- Heparan sulfate
Proteoglycans
- Major proteoglycan in cartilage
- Bind growth factors (TGF-B
- Aggrecan
2. Decorin
Describe the structure of aggrecan.
Bottle-brush-like.
The main stem is hyaluronic acid.
Sticking out of it are core proteins. Attached to core proteins are:
1. Chondroitin sulfate
2. Keratan sulfate
All GAGs contain GlcNAc as its aminosugar except these two which has GalN.
Only these two GAGs have iduronic acid as its glucoronic acid. A
Remember two TV stars named David.
GalN:
Dermatan sulfate, Chondroitin sulfate
(Goofy, David Caruso!)
Iduronic acid:
Dermatan sulfate, heparin
(Idiot, David Hasselhoff! Dahil kulay dilaw, may hepa rin!)
GAG Quiz!
A. Most abundant B. Intracellular C. Ubiquitous cell surface GAG D. Most heterogenous E. NOT sulfated, NOT attached to protein F. Also found in bacteria
A. Chondroitin sulfate (in cartilage, tendon, ligaments, bone) B. Heparin (mast cells) C. Heparan sulfate D. Keratan sulfate E. Hyaluronic acid F. Hyaluronic acid
GAG Quiz
- GalNAc, GlcUA
- GalNAc, IdUA
- GlcN, GlcUA
- Chondroitin sulfate
- Dermatan sulfate
- Heparan sulfate
GAG Quiz
- GlcNAc, Gal
- GlcN, IdUA
- GlcNAc, GlcUA
- Keratan sulfate
- Heparin
- Hyaluronic acid
Compressibility of cartilage is due to high concentrations of these two proteoglycans
- Chondroitin sulfate
2. Hyaluronic acid
GAG found in bone, cartilage and certain neurons
Chondroitin sulfate
GAG which play a role in corneal transparency
Keratin sulfate
Dermatan sulfate
Cornea? Klaro dapat.
This GAG bind to lipoprotein lipase and cause its release into the circulation.
Heparin
This GAG facilitate cell migration
Hyaluronic acid
Certain cancers induce fibroblasts to synthesize large amounts of this GAG
Hyaluronic acid
Major GAG synthesized by arterial smooth muscle cells
Dermatan sulfate
Structure of hydroxyapatite
Ca10 (PO4)6 (OH)2
Major protein in bone
Type I collagen
