Chromosomes X and Y are unlikely to be paired due to the wide difference in size. X contains thousands of genes that are vital to life. In contrast, Y is like a small black dot, whose main purpose is to guide the initiation of male development and sperm production. However, if these two distinct chromosomes are to meet and pair correctly during the denumbering division process, they must work together.
The problem has plagued scientists for decades. According to the study, published in the journal Nature, scientists at the Sloan Kettering Institute have now found the answer.
Studies in mice have found that the key to the correct pairing of X and Y is a repeating DNA sequence in PAR (pseudoautosomal region), which attracts several double-stranded fracture-related proteins to this region.
These protein clusters alter the structure of chromosomes in this region, making PAR “the hottest region in the male mouse genome for double-stranded fractures.”