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- **What are glycosylation sites on proteins?**
	- specific locations on a protein where a carbohydrate ( or glycan) can be attached.
	- process is known as glycosylation
		- essential post-translational modification
			- modulate the structure and function of proteins
- **Is there a specific sequence associated with glycosylation?**
	- usually Asn-X-Ser/Thr
		- where Asn is asparagine
		- X can be any amino acid except proline
		- and Ser/Thr are serine and threonine respectively.
	- This sequence is the consensus motif for N-linked glycosylation.
	- O-linked glycosylation, another type, does not have a strict consensus sequence and typically occurs on serine or threonine residues.
- **What is glycan shielding and how does it relate to immune escape?**
	- This is a phenomenon where the glycans attached to proteins can 'shield' the protein from recognition by the immune system.
	- Essentially, the glycans can cover up immunogenic protein regions (those parts of the protein that would elicit an immune response), thereby allowing the protein to avoid detection.
	- Glycan shielding is a key strategy that many viruses, including HIV and SARS-CoV-2, use to escape the immune system.
	- By covering up the viral proteins with glycans, these viruses can avoid being recognized and neutralized by the host's immune system
- **How do changes in the N-terminal domain affect the ability of the virus to be neutralized?**
	- The N-terminal domain (NTD) of a protein is the start of the amino acid sequence.
	- Changes in the NTD can affect the structure, stability, and function of the protein
		- which in turn can influence how the protein interacts with other molecules, including antibodies.
	- If the NTD is part of a viral protein that is recognized by neutralizing antibodies, then changes in the NTD could affect the ability of these antibodies to recognize and neutralize the virus.
	- For instance, mutations or glycosylation changes in the NTD of the spike protein of SARS-CoV-2 can reduce the efficacy of some neutralizing antibodies.
- **What types of changes have been observed in the N-terminal domain?**
	- In the context of viruses, several changes have been observed in the NTD, including point mutations, deletions, and changes in glycosylation patterns. 
	- These changes can affect the virus's transmissibility, pathogenicity, and resistance to neutralizing antibodies.
	- For instance, certain SARS-CoV-2 variants have been found to have multiple mutations and deletions in the NTD of their spike proteins, contributing to their increased transmissibility and immune evasion.

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