Term
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Definition
Repeating disacchardie units made up of an Acidic sugar(OOH) and an amino sugar(N-acetylglucosamine or glucosamine)
All GAG's except hyaluronic acid are covalently bound to protein |
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Term
| Connecting GAGs to core protein |
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Definition
Serine residue on protein provides anchor for Xylose, galactose, galactose
Glycosidic bond to OH group.
Acidic sugar is first after linkage
proteins are connected to hyaluronic via ionic bonds |
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Term
| What is the physical basis for resilience of GAGS |
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Definition
Negative charges.
Found in synovial fliud in joints, viterous humor in eye. |
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Term
| Chondroitan 4- and 6- sulfates |
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Definition
N-acetylglucosamine with sulfate on C-4 or 6 and glucuronic acid
Cartilage, tendons, ligaments, aorta.
Most abundant GAG |
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Term
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Definition
| N-acetylgalactosamine and L-iduronic acid Skin, blood vessels, heart valves |
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Term
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Definition
| N-actylglucosamine and galactose KSII found in loose CT tissue, aggregates with chondroitin KSI found in cornea. May contain additional fructose or mannose.(most heterogenous gag) |
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Term
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Definition
Glucosamine(most are sulfated) and glucuronic or iduronic acid.
α-linkage of sugars (rest of GAGS are β)
Anticoagulant found in mast cells
Heparan sulfate: some glucosamines are aceylated and fewer sulfate groups. (found in basement membrane) |
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Term
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Definition
N-acetylglucosamine and glucuronic Acid
Unsulfated, not covalently attached to protein, only GAG also found in bacteria
Serves as lubiricant and shock absorber
(synovial fluid, Jviterous humor) |
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Term
| Heparin Sulfate & chondroitin on neuronal outgrowth |
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Definition
Heparin sulfate causes oligomerization of a receptor protein tyrosine phosphatase(RPTP)
Choindroitin inhibits formation
RPTPs are surface receptors important for nervous system development, function and repair. |
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Term
| Synthesis of first stem amino sugar: Glucosamine-6-Phosphate |
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Definition
F-6-P + GLutamine(Source of NH2) -> Glucosamine-6-P + glutamate
NANA derived from GLucosamine-6-P requires 3 C from phophoenol pyruvate |
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Term
| Synthesis of carbohydrate Chains |
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Definition
Sugars attached to -OH group of serine or threonine
UDP-xylose + core protein -> Coreprotein-xylose + UDP
Via xylosyl transferase
Then 2 Gals Added, Than alternate acidic and NH2 sugars, finally add SO4 from PAPS
UDP activation d rives attachment |
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Term
| Sulfation of established carb chains |
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Definition
Occurs after sugar has been attached, Then sulfotransferases attach -SO4 groups form PAPS
Synthesis of PAPS
So4 + ATP -> PPi + adenosine-5-phosphosulfate
Adenosine-5-phosphosulfate + ATP -> ADP + 3-phosphoadenosine-5-phosphosulfate(PAPs)
Cost 3 atp equivalents
Defects in sulfation -> chondrodystrophies, skeletal |
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Term
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Definition
| Hurlers: a-L-iduronidase deficiency Coasre features, corneal clouding, dwarfing, mental retardation Hunters: Iduronate sulfatase deficiency X-linked. Wide effects, mental retardation, No corneal clouding, |
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Term
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Definition
Sanflilppo: 4 different enzyme steps that remove N-sulfated or acetylated glucosamines from heparin sulfate
Very severe NS disorders and mental retardation; Strokes
Sly: B-glucuronidase deficiency
Affects degradation of dermatan sulfate and heparin sulfate
Heptatosplenomegaly and physical deformities |
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Term
| Type II vs Type III topology |
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Definition
Signal sequence is not cleaved(internal)
Position of positively charged AA relative to signal anchor determines which end of protein occurs in lumen of ER(+AA side = Cytosol)
Type II COO- in lumen
Type III: COO- in cytosol. |
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Term
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Definition
Added sequentially to Ser/Thrf rom nucleotide precursors
Glycosyltransferases catalyze addition of sugars.
In collagen Hydroxylysine provides link and is vitamin C dependent
A anitgen: GalNAc to O oligosacs
B antigen: Gal to O oligosacs |
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Term
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Definition
First added as high mannose containing structure from dolichol
Asaparagine linked signal(Asn-X-Ser/Thr
Dolichol is attached to oligosacs by pyrophosphate link. |
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Term
| Synthesis of glycoproteins |
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Definition
| Sugar nucleotides are precursors UDP: Glucose, galactose, N-acetyglucosamine GDP: Mannose, Fructose CMP: NANA |
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Term
| Protein processing(proteolytic cleavage) occurs in transit form ER to secretory vesicles |
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Definition
Furin processes proteins in constitutive pathway
Proalbumin -> albumin via furin endoprotease
Proinsulin -> insuline requires protein convertase 2 and 3, regulated secretion. |
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