Gene X encodes an enzyme that is expressed in the skin, the brain and the heart.
ID: 9612 • Letter: G
Question
Gene X encodes an enzyme that is expressed in the skin, the brain and the heart. Skinny, brainy, hearty are three genes that encode three tissue-specific transcription factors that activate the expression of gene X in the skin, the brain, and the heart, respectively. A student has isolated a mutant mouse in which the enzyme activity of X is greatly reduced in the brain, but is normal in the skin and the heart. The expression level of skinny, brainy, and hearty is normal in this mouse and there is no mutation in any of the three genes. Propose a simple explanation for the lack of X activity in the brain in the mutant mouse. (Assume that there is no alternative splicing for gene X in the three tissues.)Explanation / Answer
The transcription factors skinny, brainy and hearty are expressed in normal concentrations. These transcription factors need to activate the expression of X gene in skin, brain and heart. When the activity of X in the brain it indicates that the presence of an inhibitor or regulator. This inhibitor reduces the activity of X when not required in normal concentrations.
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