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The SRY protein is a monomeric 203 residues long polypeptide. It is a transcriptionnal factor, more precisely a transcriptionnal activator of the Müllerian Inhibiting Substance (MIS gene). It is encoded by the testis-determining sex gene and is itself involved in the sex determination in mammels by being responsible for the male sexual developement.

History

After centuries of unfounded theories mainly based on environmental factors, the first molecular theory concerning the sex determination appears in 1891. At this time, the german biologist H. Henking was studying sperm formation in wasps. He noticed that some wasp sperm cells own 12 chromosomes whereas some only own 11. As this chromosome look different from the others during the meiosis process, he suspected it to play a role in sex determination, without any proof. He chose to name it the "X chromosome", considering its mysterious shape. Ten years later, C. E. McClung saw that the X chromosome behaved differently during the meiosis and was only present in half the sperm cells of grasshoppers. As the main characteristic that varies in 50/50 proportions among zygotes is the sex, McClung suspected the X chromosome to be implicated in sexual development.

It has been shown that a mutation of SRY increase male to female sex reversal for 15% REF NECESSAIRE

SRY gene

The SRY gene encodes the SRY protein. It is located on the Y chromosom.

Structure

The SRY-HMG domain

SRY-HMG stands for Sex determining Region Y - High Mobility Domain It is a approximately 80 residues domain. It mediates minor groove DNA binding proteins. Twisted L shape : Concave surface. 3 helices & N and C end strands. Binds the DNA by its minor groove. 2 kinds of HMG domain:

• HMG1
• HMG2

General structure of SRY

3 domains:

• N-term domain
• Central domain
• C-term domain

Structure of the DNA target site

Function

Sex determining

It acts like a sex determinator thanks to it transcriptionnal activity. It inhibits the developpement of female sex structure in th embryonnic individual.

Implication - Future for SRY ?

Disease

Relevance

Structural highlights

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