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Lactase persistence is very high among northern Europeans, especially Irish people. Worldwide, most people are lactase non-persistent, [1] and are affected by varying degrees of lactose intolerance as adults. However, lactase persistence and lactose intolerance can overlap.
[23] [24] In areas with lactase persistence, it is believed that by domesticating animals, a source of milk became available while an adult and thus strong selection for lactase persistence could occur; [21] [25] in a Scandinavian population, the estimated selection coefficient was 0.09-0.19. [25]
Lactase persistence in humans evolved relatively recently (in the last 10,000 years) among some populations. Around 8,000 years ago in modern-day Turkey, humans became reliant on newly-domesticated animals that could be milked; such as cows, sheep, and goats. This resulted in higher frequency of lactase persistence. [79]
The majority of humans actually follow this protocol as well, and down-regulate lactase production around 3-5 years of age. Interestingly, though, the majority of caucasians, mainly those from northern european background, continue to have elevated lactase activity all the way into adulthood, and so they exhibit “lactase persistence”.
The MCM complex consisting of MCM6 (this protein) and MCM2, 4 and 7 possesses DNA helicase activity, and may act as a DNA unwinding enzyme.The hexameric protein complex formed by the MCM proteins is a key component of the pre-replication complex (pre-RC) and may be involved in the formation of replication forks and in the recruitment of other DNA replication related proteins.
Lactase is an enzyme that some people are unable to produce in their small intestine. [2] Technology to produce lactose-free milk, ice cream, and yogurt was developed by the USDA Agricultural Research Service in 1985. [3]
In humans, in non-dairy consuming societies, lactase production usually drops about 90% during the first four years of life, although the exact drop over time varies widely. [190] Lactase activity persistence in adults is associated with two polymorphisms: C/T 13910 and G/A 22018 located in the MCM6 gene. [191]
Many adult humans lack the lactase enzyme, which has the same function as β-galactosidase, so they are not able to properly digest dairy products. β-Galactose is used in such dairy products as yogurt, sour cream, and some cheeses which are treated with the enzyme to break down any lactose before human consumption. In recent years, β ...