The nuclear localization signal (NLS) is, in general, not removed when the protein is matured.
A nuclear localization signal or sequence (NLS) is an amino acid sequence that 'tags' a protein for import into the cell nucleus by nuclear transport. Typically, this signal consists of one or more short sequences of positively charged lysines or arginines exposed on the protein surface. Different nuclear localized proteins may share the same NLS. An NLS has the opposite function of a nuclear export signal (NES), which targets proteins out of the nucleus.
NLS could be divided into 5 classes.
Class 5 NLSs is specific only to plants, in contrast with the other classes, all of which are functional in yeast, plants and mammals.
Souce: NovoPro 2019-02-22