83.2k views
5 votes
What are the tags and their location on either the C- or N- Terminus?

1 Answer

3 votes

Final answer:

N-terminal and C-terminal refer to the ends of proteins where amino and carboxyl groups are free, respectively. The N-terminal is used to determine sequence and is typically written first, on the left, while the C-terminal is on the right. Transmembrane proteins may have varied locations for these termini, based on how they insert into the membrane.

Step-by-step explanation:

Understanding N-Terminus and C-terminus Tags on Proteins

The N-terminal end of a protein or polypeptide is where the amino group is free and is known as the N-terminal amino acid. Methods like Sanger's, Edmann's, and Dansyl chloride reagents are used for determining the N-terminal amino acids. Conversely, the C-terminal end of a protein is where the carboxylic group is free, known as C-terminal amino acid, and can be detected using reagents like hydrazine.

During the representation on paper, the sequence of amino acids in a peptide or protein begins with the N-terminus on the left and ends with the C-terminus on the right. The N-terminus typically has a free ammonium group (–NH3), whereas the C-terminus has a free carboxyl group (-COOH).

Transmembrane proteins' N- and C-termini locations can vary depending on how these proteins insert into the membrane during synthesis. For example, with a single-pass transmembrane protein like glycophorin A, the N-terminal end is often exposed to the outside of the cell.

The N-end rule suggests that certain amino acids at the N-terminus can either stabilize or destabilize the protein, affecting its half-life. This 'punctuation system' of stabilizing and destabilizing amino acids is essential for the protein's function and degradation.

User Roozbubu
by
8.3k points
Welcome to QAmmunity.org, where you can ask questions and receive answers from other members of our community.