Chromosomal proteins impart both structure and regulation to DNA sequences. Characterization of specific chromosomal proteins will lead to better understanding of both chromatin structure and regulation of gene expression. The process of spermatogenesis involves a complex program of ordered gene expression as well as a series of nuclear events that are unique to male gamete differentiation. For example, meiosis describes the process by which homologous chomosomes pair, undergo genetic recombination, and finally separate to yield haploid cells. During this period several testis-specific histone variants appear.
Histones are small proteins that are responsible for packaging DNA into chromosomes.
H1t is one of the novel variants made during meiosis, and we have isolated and sequenced the H1t gene. Later during spermatogenesis, a complete reorganization of the nucleus occurs. Histones of all kinds are largely eliminated. For a brief period the so-called nuclear transition proteins appear. They are then replaced by the protamines, which are very small, basic proteins that organize DNA in the nucleus of the sperm cell.