I don't know if this is it, interesting read tho. Google for full version
Equal by Dan Gwartney, MD
Equal by Dan Gwartney, MD
When testosterone enters a cell (for the biology geeks, this is restricted to the genomic effects of testosterone), it binds with an androgen receptor. There are different co-factors in the various cell types (skeletal muscle, fat, liver, etc.) that either enhance or impair the ability of the receptor to connect with and stimulate the cell to respond. These co-factors attach onto the testosterone-androgen receptor complex and travel as a unit to the nucleus, and bind to the chromosomes (DNA) at specific androgen response elements— think of it as assigned parking spaces. The complex then dimerizes (pairs up with another complex) to actually turn on the testosterone-sensitive genes.
Genes are information; they do not function as anything other than data storage. In order for the information they contain to become new cell structures or change function, the information has to re-enter the cell in a form that the machinery of the cell can understand. This occurs through transcription. Transcription creates a ‘chemical memo,’ or instructions from the head office. The longer the CAG repeat, the higher the degree of separation, and the less likely the message is to be affected.
Of course, the interest of bodybuilders and athletes is any effect of CAG repeats on physical performance or body composition. Men with longer CAG repeats suffer from all sorts of performance handicaps compared to their short-CAG cohorts. Lengthening of CAG repeats may contribute toward decreased muscle mass, increased body fat, weaker bones, decreased aggressiveness, increased depression, reduced insulin sensitivity, and harm cardiovascular health through elevations in heart rate and blood pressure.12,16
Some interesting observations were noted. There is a racial trend in CAG repeat length; with men of African descent having fewer CAG repeats, followed by Caucasians, then East Asians.