The smallest unit of life is a cell, which contains numerous
protein molecules. Most of the functions critical to the cell’s survival
are performed by these proteins located in its different organelles, usually
called ‘‘subcellular locations”. Information of subcellular
localization for a protein can provide useful clues about its function. To
reveal the intricate pathways at the cellular level, knowledge of the
subcellular localization of proteins in a cell is prerequisite. Therefore,
one of the fundamental goals in molecular cell biology and proteomics is to
determine the subcellular locations of proteins in an entire cell. It is
also indispensable for prioritizing and selecting the right targets for drug
development. Unfortunately, it is both time-consuming and costly to
determine the subcellular locations of proteins purely based on experiments.
With the avalanche of protein sequences generated in the post-genomic age,
it is highly desired to develop computational methods for rapidly and
effectively identifying the subcellular locations of uncharacterized
proteins based on their sequences information alone. Actually, considerable
progresses have been achieved in this regard. This review is focused on
those methods, which have the capacity to deal with multi-label proteins
that may simultaneously exist in two or more subcellular location sites.
Protein molecules with this kind of characteristic are vitally important for
finding multi-target drugs, a current hot trend in drug development.
Focused in this review are also those methods that have use-friendly
web-servers established so that the majority of experimental scientists can
use them to get the desired results without the need to go through the
detailed mathematics involved.