The Proteome:

• The proteome is the entire set of proteins expressed by a genome

• The proteome is larger than the number of genes, particularly in eukaryotes, because more than one protein can be produced from a single gene as a result of alternative RNA splicing

• Not all genes are expressed as proteins in a particular cell type

  • Genes that do not code for proteins are called non-coding RNA genes and include those that are transcribed to produce tRNA, rRNA, and RNA molecules that control the expression of other genes.

• The set of proteins expressed by a given cell type can vary over time and under different conditions

  • Some factors affecting the set of proteins expressed by a given cell type are the metabolic activity of the cell, cellular stress, the response to signalling molecules, and diseased versus healthy cells.