minichromosome maintenance complex component 6
The MCM6 gene provides instructions for making part of the MCM complex, a group of proteins that functions as a helicase. Helicases attach to particular regions of DNA and temporarily unwind the two spiral strands of these molecules. When a cell prepares to divide to form two cells, helicases unwind the DNA so that it can be copied. The DNA that makes up the chromosomes is duplicated (replicated) so that each new cell will get a complete set of chromosomes. Helicases are also involved in the production of RNA, a chemical cousin of DNA.
A specific DNA sequence within the MCM6 gene called a regulatory element helps control the activity (expression) of a nearby gene called LCT. The LCT gene provides instructions for making an enzyme called lactase. This enzyme helps to digest lactose, a sugar found in milk and other dairy products. Lactose intolerance in adulthood is caused by gradually decreasing expression of the LCT gene after infancy, which occurs in most humans.
At least four variations have been identified in the regulatory element that modulates LCT gene expression. These variations change single DNA building blocks (nucleotides) in the regulatory element. Each of the variations results in sustained lactase production in the small intestine and the ability to digest lactose throughout life. People without these changes have a reduced ability to digest lactose as they get older, resulting in the signs and symptoms of lactose intolerance.
- DNA replication licensing factor MCM6
- MCM6 minichromosome maintenance deficient 6 (MIS5 homolog, S. pombe)
- minichromosome maintenance deficient (mis5, S. pombe) 6
- minichromosome maintenance deficient 6 homolog
- MIS5 homolog