Protamines substitute for histones in the chromatin of sperm during the haploid phase of spermatogenesis, and are the major DNA-binding proteins in the nucleus of sperm in many vertebrates. They package the sperm DNA into a highly condensed complex in a volume less than 5% of a somatic cell nucleus.
Many mammalian species have only one protamine (protamine 1); however, a few species, including human and mouse, have two. This gene encodes protamine 2, which is cleaved to give rise to a family of protamine 2 peptides. Alternatively spliced transcript variants have also been found for this gene. [provided by RefSeq, Sep 2015]
Transition protein-1 is a spermatid-specific product of the haploid genome which replaces histone and is itself replaced in the mature sperm by the protamines (see PRM1, MIM 182880; PRM2, MIM 182890) (Luerssen et al., 1990 [PubMed 2249851]).[supplied by OMIM, Ma