Protamines are small, arginine-rich, nuclear proteins that replace histones late in the haploid phase of spermatogenesis and are believed essential for sperm head condensation and DNA stabilization.

Function

When mixed with insulin, protamines slow down the onset and increase the duration of insulin action (see NPH insulin).

Protamine sulfate is an antidote for heparin.^[1]

Examples

Mice, humans, and certain fish have 2 or more different protamines, whereas the sperm of bull, boar, rat, rabbit, guinea pig, and ram have one form of protamine.

Human

The 2 human protamines are denoted PRM1 and PRM2.

Fish

Examples of protamines from fish are:

• salmine from salmon
• clupeine from herring sperm (Clupea)
• iridine from rainbow trout
• thinnine from tunafish (Thunnus)
• stelline from starry sturgeon (Acipenser stellatus)
• scylliorhinine from dogfish (Scylliorhinus)

References

1. ^ Byun Y, Chang LC, Lee LM, Han IS, Singh VK, Yang VC (2000). "Low molecular weight protamine: a potent but nontoxic antagonist to heparin/low molecular weight protamine". ASAIO J. 46 (4): 435–9. PMID 10926141.