Dosage Compensation Mechanism
As human females have two X chromosomes, this means they have the ability to produce twice as much X-linked gene product, this Dosage Compensation Mechanism is responsible for keeping levels of the X-linked gene product similar in both males and females. Therefore, such a mechanism only exists in females. Dosage compensation requires RNA polymerase, Tsix transcript and Xist transcript as well as the X chromosomes of developing embryonic cells. Note that each transcript is transcribed on one chromosome each. Xist acts as to ensure inactivation of X chromosome whereas Tsix ensures X chromosome remains active. Such activity is carried out from the X inactivation centre [1]., also known as XIC. The XIC is located at the centromere and is where decativation of the X Chromosome begins[2] This mechanism follows the process of X-inactivation, also termed Lyonization or single active X principle, in which regardless of the amount of X chromosomes are present, all but one are inactivated. However, although one of the X chromosomes is said to be inactivated, there is still around 15% of the genes on the inactivated X chromosome which aren't inactivtaed. [3]