Abstract
BackgroundThe rapid completion of genome sequences has created an infrastructure of biological information and provided essential information to link genes to gene products, proteins, the building blocks for cellular functions. In addition, genome/cDNA sequences make it possible to predict proteins for which there is no experimental evidence. Clues for function of hypothetical proteins are provided by sequence similarity with proteins of known function in model organisms.ResultsWe constructed a two-dimensional protein map and searched for expression of hypothetical proteins in rat brain. Two-dimensional electrophoresis (2-DE) with subsequent in-gel digestion of spots and matrix-assisted laser desorption/ionization (MALDI) spectrometric identification were applied. In total about 3700 spots were analysed, which resulted in the identification of about 1700 polypeptides, that were the products of 190 different genes. A number of hypothetical gene products were detected (30 of 190, 15.8%) and are considered brain proteins.ConclusionsA major finding of this study is the demonstration of the existence of putative proteins that were so far only deduced from their nucleic acid structure by a protein chemical method independent of antibody availability and specificity and unambiguously identifying proteins.
Highlights
The rapid completion of genome sequences has created an infrastructure of biological information and provided essential information to link genes to gene products, proteins, the building blocks for cellular functions
Some of them were represented by strong spots and the present study shows that they are expressed in rat brain
Hypothetical proteins with enzymatic activity identified by proteomics in the rat brain may be useful for determination of metabolic disorders in the brain, including inborn errors of metabolism and form the basis for physiological or pharmaceutical studies
Summary
The rapid completion of genome sequences has created an infrastructure of biological information and provided essential information to link genes to gene products, proteins, the building blocks for cellular functions. The amount of genome sequence data available is enormous, with only more to come. At this time, sequencing of more than 700 genomes is either finished or in progress, and results may be found in various public databases [1]. With the availability of genome sequences, increasing attention has focused on identifying the complete set of mammalian genes, both protein-coding and non-protein-coding. As various analyses [2,3] have revealed, different annotation criteria lead to different sets of predicted genes, and even the true number of proteincoding genes remains uncertain. A draft sequence of the mouse genome and comparative analyses with the human sequence has been published [4].
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