Testicular-determining factor
| Testicular-determining factor | ||
|---|---|---|
|
||
| TDF (HMG domain, green) with DNA (blue) according to PDB 1J46 | ||
| Properties of human protein | ||
| Mass / length primary structure | 204 amino acids; 23.9 kDa | |
| Identifier | ||
| Gene names | SRY ; TDF | |
| External IDs | ||
| Occurrence | ||
| Parent taxon | Euteleostomi | |
| Orthologue | ||
| human | mouse | |
| Entrez | 6736 | 21674 |
| Ensemble | ENSG00000184895 | ENSMUSG00000069036 |
| UniProt | Q05066 | Q2T9H0 |
| Refseq (mRNA) | NM_003140 | NM_011564 |
| Refseq (protein) | NP_003131 | NP_035694 |
| Gene locus | Chr Y: 2.71 - 2.72 Mb | Chr Y: 1.95 - 1.95 Mb |
| PubMed search | 6736 |
21674
|
The testis determining factor , English testis determining factor (TDF) is a protein which by the gene sex determining region of the Y , shortly SRY gene on the short arm of the Y chromosome coding is. TDF determines whether a testicle begins to develop from the initially indifferent gonadal system. If it is missing, an ovary arises from this . Its presence or functionality is - apart from the question of whether a sperm cell with a Y chromosome or one with an X chromosome fertilized the egg cell - the primary trigger for the development into a male individual .
function
The human SRY gene is first transcribed in the seventh week of embryogenesis and encodes the TDF protein, which acts as a transcription factor . This protein regulates the expression of numerous other genes in the genome and initiates sex differentiation . B. stimulates certain somatic cells to develop into testosterone-producing Leydig cells .
In the absence of the TDF protein, Muller's ducts form during embryonic development. But there is no development of the Wolffian corridors . So if the SRY gene (due to a mutation) has no function or the TDF or testosterone perception system does not work, XY fetuses develop into sterile, female-looking creatures (so-called XY women ).
The DAX1 gene on the X chromosome prevents the testes from developing when it is overexpressed (this is done by duplicating the DAX1 gene). The duplication of DAX1 results in a gender reassignment of male individuals. The result is the emergence of sterile XY women who look feminine. This is an example of pseudohermaphrodites in which the chromosomal (XY) and the phenotypic , thus the genital sex, do not match.
Another example are male individuals who do not have a Y chromosome. In these, the SRY region was translocated to one of the X chromosomes or one of the autosomes as part of the maturation division during spermatogenesis . This causes embryonic development to follow the male path. This case appears to occur at a frequency of 1 in 20,000 in men, i.e. This means that 5 out of 100,000 men can accordingly be classified as XX men , and that this is one of the causes of male infertility because they do not have the genes of the Y chromosome which are necessary for the formation of mobile sperm .
history
In 1959 it could be shown that the Y chromosome is the carrier of the gene for the TDF in humans and mice. In 1966, based on the effects of translocations and chromosome shortening ( deletions ), the gene localization was narrowed to the short arm of the Y chromosome.
It has been known since the late 1980s that region 1 of the short arm of the Y chromosome encodes the factor as the sex determining region of Y (SRY); in the meantime, the exact locus for the now identified SRY gene is given as Yp11.3.
See also
Web links
Individual evidence
- ↑ Sinclair, AH (1990): A gene from the human sex-determining region encodes a protein with homology to a conserved DNA-binding motif. In: Nature. 346: 240-245. PMID 1695712