The
proteome is defined as the entire
collection of
proteins, in their
modified and
active forms that are present in a cell at any one time. It is changes in the proteome, much more so than any change in the
genome, that is reflected by changes in the
environment. The purpose behind the study of proteomics is that many cells, whether in tissues in a whole
organism or as single cells in a fluctuating
environment, are defined not by the presence of a gene in the
DNA, but by the expression of those
genes in the form of proteins in their many varying forms. Such changes as
tissue types,
carbon sources,
stage in life of the
cell, or even
temperature can alter the
expression level of a given protein, or can alter the
post-translational modification of the protein such that it is
secreted instead of attached to the
plasma membrane, or can alter the
half-life of a protein.
There's also a
Massachusetts-based company called
Proteome (www.proteome.com) that offers complete (well, as complete as can be) protein databases for several organisms:
yeast (
S. cerevisiae and
S. pombe),
roundworms (
C. elegans), and, most recently added,
humans. The company provides this service
free to
academic users, and for a small fee to
corporations and independent
users. The
databases are organized in such a way that one can search by
gene name,
protein function, or by
sequence.
Personally, I've found it invaluable as a research tool.
Other sources:
http://www.sdu.dk/Nat/CPA/index.html -- Centre for Proteome Analysis, University of Southern Denmark, Odense, Denmark
http://www.ebi.ac.uk/proteome/ -- European Bioinformatics Institute, Hinxton, Cambridge, UK
http://www.proteome.co.uk/ -- Proteome Sciences, Cobham, Surrey, UK