Y 염색체 구조에 대해 정리해보겠습니다. 아래 그림처럼 Y염색체에는 male-specific 구역이 있습니다.
Pseudoautosomal (수도오토조멀) is telomeric sequences found on both X and Y chromosomes. 짧은 사슬모양의 중합체로 X와 Y염색체 모두 발견됩니다.
Y염색체 중에서 male specific 구역은 4개 부분으로 이뤄져있는데요. 1. X-transposed 란 구역은 X염색체와 거의 99% 일치합니다. 2. X-degenerate 부분은 X-linked gene과 60~90% 정도 일치하는 부분이 있고요. 27개 gene 중에 16개는 기능적인 역할이 있고 그중에 SRY gene이 있습니다. 3. Ampliconic는 길고 긴 반복되는 gene으로 되어있고요. 4. Heterochromatic은 tandem이 반복적으로 나타나는 구역입니다.
In male specific region (MSY 95% of Y chromosome) consists of 4 parts; 1) X transposed part which 99% are identical to X chromosome, 2) X-degenerate part which contains genes with 60~96% sequence identify to X-linked genes and 27 genes (only 16 genes are functional) including SRY gene, 3) ampliconic region which is long MSY repeats containing 8 palindromic sequences, and 4) heterochromatic (tandem repeats of low sequence complexity)
palindromes (회문)은 저번에도 설명했지만 앞으로 읽어도 뒤로 읽어도 똑같은걸 말합니다. 만약 GGTACC라는 sequence가 있다고 하면 complementary strand 역시 CCATGG이겠지요. 그래서 만약 복제과정에서 문제가 생긴다면 헤어핀 모양처럼 만들어져서 알아서 고쳐지게 됩니다. 이걸 gene conversion이라고 부르는데 한국말로는 뭐라 부르는지는 모르겠네요ㅠ
In terms of palindromes, Y chromosome contains stretches of DNA in such identical mirror copies of each other. If one of these section makes a hairpin bend in the middle, it appears capable of donating an intact gene to fix a defective copy on the neighboring section. So the Y chromosome seems to have its own self-repair mechanism, a process called gene conversion, maintaining the integrity of the genes without crossover.
Deletion in regions of Y chromosome lead to female or to infertile in males, sometimes there will not affect. SRY gene found near pseudoautosomal region is needed for male determination. In normal exchange between X and Y chromosomes in pseudoautosomal region, it becomes normal female. However, regarding abnormal exchanging between X and Y chromosomes outside of pseudoautosomal region, If SRY male specific gene is relocated onto X chromosome, then this individual become phenotypic male with XX genotype.
Reference: http://universe-review.ca/R11-14-Ychromosome.htm 정말 잘 정리되어있습니다. GOOOOD!!