Sequence analysis of genomic DNA, which
started in 1990s on a full scale, developed rapidly during the last
decade. The entire sequence of genomic DNA is now available for many
organisms including higher plants, animals and human. Based on this
analysis, the number of genes in the genomes have been estimated. For
example, about 32,000 genes encoding proteins are considered to be
present in the human genome, suggesting that the human proteome consists
of at least 32,000 proteins. Functions of only 50% of the proteins have
been assigned by retrieval of the available databases. Similar
situations can also be found in other organisms, suggesting a prime need
to determine the functions of the unknown proteins and their functional
network by proteome analysis
