Gene expression

Gene expression (also protein expression or often simply expression) refers to the multi-step process that begins with protein biosynthesis (spanning from the transcription of a gene into messenger RNA (mRNA) to its translation into protein) and is followed by folding, post-translational modification[?] and targeting. The amount of protein that a cell expresses depends on the tissue, the developmental stage[?] of the organism and the metabolic or physiologic state of the cell.

Indirectly, expression may be analysed with microarray technology, which can provide a rough measure of the concentration of particular mRNAs. While the name is a misnomer, this type of analysis is often referred to as expression profiling[?]. , but the term "gene expression" puts emphasis on the first step in the process, translation, because the abundance of mRNA can be estimated directly using microarray methods.

The level of expression or activity of a gene depends in part on the expression levels of other genes called transcription factors, which often regulate that gene specifically.

Each gene thus may be regarded as a node in a network, with input - relevant proteins, and output the level of expression. The node itself is a function which can be obtained by combining basic functions, or gates, of the two outputs, which are now understood. It is similar to having boolean function computed using the basic AND OR and NOT gates in electronics. These fuctions carry information processing[?] within cell and determine celular behaviour. The basic drivers within cells are levels of some proteins, which determine both spatial (tissue related) and temporal (developmental stage) coordinate of the cell, and also its memory. The gene networks are only beginning to be understood, and it is a next fundamental step for biology - understanding nodal functions for each gene, and thus modeling behaviour of a cell.

External Link

• NCBIs Gene Expression Omnibus (http://www.ncbi.nlm.nih.gov/geo/)