StAR-related lipid transfer domain protein 8 (STARD8) also known as deleted in liver cancer 3 protein (DLC-3) 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...

 that in humans is encoded by the STARD8 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...

 and is a member of the DLC family.

Structure and function

The protein is 1103 amino acids long, which like other DLC proteins consists of a sterile alpha motif

Sterile alpha motif

Sterile alpha motif is a putative protein interaction module present in a wide variety of proteins involved in many biological processes. The SAM domain that spreads over around 70 residues is found in diverse eukaryotic organisms...

 (SAM), RhoGAP

RhoGAP domain

RhoGAP domain is an evolutionary conserved protein domain ofGTPase activating proteins towards Rho/Rac/Cdc42-like small GTPases.-Human proteins containing this domain :ABR; ARHGAP1; ARHGAP10; ARHGAP11A; ARHGAP11B; ARHGAP12; ARHGAP15; ARHGAP17;...

 and a StAR-related lipid-transfer (START) domains.

The protein is a Rho GTPase-activating protein (GAP), a type of protein that regulates members of the Rho family of GTPases

Rho family of GTPases

The Rho family of GTPases is a family of small signaling G protein , and is a subfamily of the Ras superfamily. The members of the Rho GTPase family have been shown to regulate many aspects of intracellular actin dynamics, and are found in all eukaryotic organisms including yeasts and some plants...

. STARD8 is characterized as activating Rho GTPases

Rho family of GTPases

The Rho family of GTPases is a family of small signaling G protein , and is a subfamily of the Ras superfamily. The members of the Rho GTPase family have been shown to regulate many aspects of intracellular actin dynamics, and are found in all eukaryotic organisms including yeasts and some plants...

. Its expression inhibits the growth of human breast and prostate cancer cells in culture.

Tissue distribution and pathology

The protein is expressed in tissues throughout the body, but is absent or reduced in many kinds of tumor

Tumor

A tumor or tumour is commonly used as a synonym for a neoplasm that appears enlarged in size. Tumor is not synonymous with cancer...

 cells.

While there are no known disorders caused by STARD8, partial loss of the STARD8 gene occurs in cases of craniofrontonasal syndrome

Craniofrontonasal syndrome

Craniofrontonasal syndrome is an X-linked syndrome which is more severe in females than males. Often males will have only hypertelorism , whereas females have frontonasal dysplasia, craniofacial asymmetry, bifid nasal tip, grooved nails, wiry hair and anomalies of the thoracic skeleton.Most cases...

 where the EFNB1

EFNB1

Ephrin-B1 is a protein that in humans is encoded by the EFNB1 gene.Mutations in this protein are responsible for most cases of craniofrontonasal syndrome.-Further reading:...

gene (which causes the syndrome) is completely deleted.