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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. It may allow for denser packaging of DNA in spermatozoon than histones, but it must be decompressed before the genetic data can be used for protein synthesis. Genes that are essential for early embryonic development are still bound to ordinary histones, comprising about 4 percent of the DNA in spermatozoons.[1]
[edit] Medical UsesWhen 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.[2] [edit] ExamplesMice, 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. [edit] HumanThe 2 human protamines are denoted PRM1 and PRM2. [edit] FishExamples of protamines from fish are:
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