What is the specific role of Xist in mammalian X-inactivation?
a. It encodes a protein that triggers heterochromatin formation on one X and suppresses it on the other X.
b. It is a DNA element acting as a binding site for proteins that trigger heterochromatin formation.
c. It produces an antisense RNA that prevents inactivation of one X chromosome.
d. It produces an RNA that accumulates on the future inactive X.
e. It encodes a transcription factor that activates genes producing proteins that function in X-inactivation.
Ans: d
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