glycolipids and glycoproteins Flashcards
mannose-6-P is synthesized from-
fructose-6-P using phosphomutase isomerase
amino sugars are all derived from-
glucosamine-6-P
glucosamine-6-P is derived from-
fructose-6-P using aminotransferase
N-acetylglucosamine-6-P is derived from-
fructose-6-p –> glucosamine-6-P using N-acetyltransferase
2 main components of GAGs
- uronic acid (glucuronic or iduronic)
- N-acetlated hexosmaine (often sulfated)
what provides the sulfates for sulfating of proteoglycans?
PAPs= 3’-phsophoadenosine and 5’-phosphosulfate, enzyme - sulfotransferase
proteoglycans will be linked by-
linker proteins
3 basic qualities of glycoproteins
branched
mannose rich
contain NANA
where are carbohydrate chains added to glycoproteins?
serine or threonine residues
what is dilichol phosphate?
involved in transferring branched sugar chains to the amide of asparagine
I-cell disease
-caused by absence of mannose-6-P on lysosomal enzymes, they never reach lysosome, instead enter blood; substrates accumulate in lysosomes (def of n-acetylglucosamine phosphotransferase)
2 sphingosine derivatives
cerebroside
ganglioside
describe ganglioside
longer chains than cerebroside
describe type A blood
GalNAc, enzyme = N-acetyl galactosamine transferase, anti-B antibodies
describe type B blood
gal, enzyme = galactosyltransferase, anti-A antibodies
describe type O blood,
no antigens, no enzymes, both anti-A and and-B antibodies
describe type AB blood
both antigens, both enzymes, no antibodies
mucopolysaccharidoses are caused by-
accumulation of partially degraded GAGs
hunter syndrome
X linked
iduronate sulfatase def
H/D
hurler syndrome
AR
a-L iduronidase def
H/D
mucopolysaccharidosis type IV
AR
n-acetylglucosamine-4-sulfatase def
D/C
nieman-pick
def sphingomyelinase
tay-sachs
AR
mut in hexaminose A = decreased lipid degradation in lysosome that results in lipid accumulation “onion peel” and cherry red retina
