(a) WHY does it make sense that a receptor on the liver that recognizes and clea
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Question
(a) WHY does it make sense that a receptor on the liver that recognizes and clears circulating glycoproteins would recognize an asialoglycoprotein moiety ???
(b) Why might one vaccine against HIV that is directed against an epitope on gp120 on the viral coat not block the binding of ALL HIV strains to host immune cells with functional CD4+ and CXCR5 receptors on their cell surface?
(c) If you were to use an antibody to identify a N-acetylglucosamine ( GlCNAC) transferase in a cell, what compartment of the cell would you expect to find this enzyme?
Explanation / Answer
b. HIV virus has RNA genome and it replicates through a dsDNA intermediate. It has reverse transcriptase enzyme which reverse transcribes its RNA genome to DNA. This enzyme, which is an RNA dep DNA pol, lacks efficient proof reading activity. Due to this, the repliation of virus is highly error prone. The virus mutates at a higher rate. This is the reason that a vaccine made against a single gp120 do not confer resistant to all virus.
The mutation alters the affinity and avidity of the antigen. These changes in binding affinity are responsible for severity of certain strains over others. This means, mutations may change the gp 120 in such a way that it either binds to target with high affinity, or low affinity, or binding affinity remians unaltered.
c. N-acetylglucosamine transferase is present both in cytoplasm and nucleus. GlcNAC is a dynamic modulator of functioning of cells and molecules. The molecule associates with proteins and change the dynamics of proteins. The enzyme GlcNAC is present both in cytoplasm and nucleus of cells. Hence, the enzyme is expected to find in nucleus and rough endoplasmic reticulum where glycosylation of proteins occur.
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