Protamine-2 (PRM2)

Protamine-2 (PRM2) is a small, arginine-rich nuclear protein expressed predominantly during the late stages of spermatogenesis, where it replaces histones in elongating spermatids[2][4]. PRM2 binds to the major groove of DNA, neutralizing its negative charge and enabling the DNA to coil into tightly packed toroidal structures, resulting in extreme chromatin condensation necessary for mature sperm function[1][2][3][4]. Unlike protamine-1, PRM2 is synthesized as a precursor protein that undergoes proteolytic processing after chromatin incorporation[2]. PRM2 also binds zinc, forming homodimers that help organize and stabilize sperm chromatin[1][2]. In humans and mice, the ratio of protamine-1 to protamine-2 is crucial for normal sperm head morphology, DNA integrity, and male fertility, with aberrations linked to infertility or subfertility[3][4]. PRM2 is not considered a traditional therapeutic drug target (such as a receptor or enzyme), and there are no known drugs that interact directly with PRM2. However, the PRM1/PRM2 ratio is a potential biomarker for sperm quality and male fertility assessment[4].

Other names

Basic nuclear protein HPI1Basic nuclear protein HPI2Basic nuclear protein HPS1Basic nuclear protein HPS2Sperm histone HP4Sperm histone HP2Sperm histone HP3P2'CT94.2Sperm histone P2Sperm protamine P2Sperm protamine P4P2''Sperm protamine P3cancer/testis antigen family 94 member 2testicular secretory protein Li 40