Flashcards in Biochemistry Deck (173)
Another name for a proteoglycan
Sugar backbone + protein
A GAG consists of
Repeating disaccharide units of: acid sugar (glucuronic acid, iduronic acid) & amino sugar (glucosamine, galactosamine)
6 major groups of GAG include:
1. CS #1 (cartilage, bone, heart valves)
2. Hyaluronic acid (no sulfate, not covalently attached to proteins)
5. Heparan Sulfate (negatively charged, acetylated glucosamine)
6. Heparin (more sulfated than HS)
Cartilage consists of these GAGs (3)
CS, KS, hyaluronic acid
How is a GAG linked to a protein to form a proteoglycan?
Trihexoside linkage (gal-gal-xy) + serine
GAG's are synthesized using what enzymes
Who is the sulfate donor when it comes to proteoglycan synthesis?
PAPS (with sulfrotransferase)
What is I cell disease?
Inability to transport hydrolytic enzymes to lysosomes 2/2 to inability to phosphorylate mannose
* Skeletal abnormalities, psychomotor, no joint movement
* Substances accumulate in lysosome; enzymes accumulate in plasma
O-glycosidic links in glycoproteins are made by...
OH- of serine/threonine
What are several examples of glycoproteins?
Cell surface receptors, blood group Ag, collagen, fibronectin
The pathogenesis of E. coli & H. pylori as it relates to glycoproteins
E. coli: mannose in plasma membrane
H. pylori: gastric epithelium
COPI vs COP2 cellular trafficking
What about clathrin?
COP1: retrograde: Golgi --> ER
COP2: anterograde: ER --> Golgi
Clathrin: Golgi --> Lysosomes; Plasma membrane --> Endosomes
What GAG can be injected into the joints of patients with osteoarthritis?
Fabry's disease: deficient enzyme
Gaucher's disease: deficient enzyme
Niemann-Pick disease: deficient enzyme
Tay-Sachs disease: deficient enzyme
Krabbe's disease: deficient enzyme
Metachromatic leukodystrophy: deficient enzyme
Hurler's syndrome: deficient enzyme
Hunter's syndrome: deficient enzyme
X-linked lysosomal storage disorders
Cherry-red spot macula lysosomal storage disorders
Tay-Sachs, Niemann-Pick (+HSM)
Corneal clouding lysosomal storage disorders
Fabry's disease: accumulated substrate
Gaucher's disease: accumulated substrate
Niemann-Pick disease: accumulated substrate
Tay-Sachs disease: accumulated substrate
Krabbe's disease: accumulated substrate