Nterminaalisesta

Nterminaalisesta refers to the N-terminus, also known as the amino-terminus or the amino end, of a polypeptide chain. This is the end of the polypeptide chain that has a free amino group (-NH2). In the process of protein synthesis, amino acids are added to the growing polypeptide chain one by one, starting from the N-terminus and moving towards the C-terminus. The sequence of amino acids in a protein is determined by the genetic code, and the N-terminus is the first amino acid to be synthesized.

The N-terminus often plays a crucial role in protein function. It can be involved in protein folding, protein-protein interactions, and the recognition and targeting of proteins to specific cellular locations. For example, signal sequences, which direct proteins to particular organelles or for secretion, are often found at the N-terminus. Additionally, post-translational modifications, such as the removal of the initial methionine residue by an enzyme called methionine aminopeptidase, can occur at the N-terminus, further influencing protein activity and stability. The N-terminal amino acid can also be subject to N-end rule degradation, a pathway that regulates protein half-life based on the identity of its N-terminal residue. Understanding the N-terminus is therefore fundamental to comprehending protein structure, function, and regulation.