RNA Polymerase II - N-terminus

N-terminus

The N-terminus (also known as the amino-terminus, NH₂-terminus, N-terminal end or amine-terminus) refers to the start of a protein or polypeptide terminated by an amino acid with a free amine group (-NH₂). The convention for writing peptide sequences is to put the N-terminus on the left and write the sequence from N- to C-terminus. When the protein is translated from messenger RNA, it is created from N-terminus to C-terminus.

The N-terminus is the first part of the protein that exits the ribosome during protein biosynthesis. It often contains sequences that act as targeting signals, basically intracellular zip codes, that allow for the protein to be delivered to its designated location within the cell. The targeting signal is usually cleaved off after successful targeting by a processing peptidase. Some proteins are modified posttranslationally.