Transmembrane protein 18 also known as TMEM18 is a protein

Protein

Proteins are biochemical compounds consisting of one or more polypeptides typically folded into a globular or fibrous form, facilitating a biological function. A polypeptide is a single linear polymer chain of amino acids bonded together by peptide bonds between the carboxyl and amino groups of...

 which in humans is encoded by the TMEM18 gene

Gene

A gene is a molecular unit of heredity of a living organism. It is a name given to some stretches of DNA and RNA that code for a type of protein or for an RNA chain that has a function in the organism. Living beings depend on genes, as they specify all proteins and functional RNA chains...

.

Function

Overexpression of the TMEM18 protein increases the migration

Cell migration

Cell migration is a central process in the development and maintenance of multicellular organisms. Tissue formation during embryonic development, wound healing and immune responses all require the orchestrated movement of cells in particular directions to specific locations...

 capacity of neural stem cell

Neurogenesis

Neurogenesis is the process by which neurons are generated from neural stem and progenitor cells. Most active during pre-natal development, neurogenesis is responsible for populating the growing brain with neurons. Recently neurogenesis was shown to continue in several small parts of the brain of...

s while inactivation of TMEM18 results in almost complete loss of migration activity.

The TMEM18 gene is ubiquitously expressed in both rodent and fly tissues, which suggests a basic cellular function. In the mouse brain, it is found in the majority of all cells, but is more abundant in neurons than other cell types.

Evolutionary history

The TMEM18 gene has a long evolutionary history as it is present in both plants and animals. The TMEM18 protein's amino acid sequence is well conserved, which suggests that it has retained its function since the divergence of human and plants. Interestingly, the gene seems to have been lost in two separate lineages, but is not found duplicated in any analyzed genomes. Hence, it is not essential for eukaryotic organisms, but there could be a selection against multiple copies of the TMEM18 gene.