protamine n : a simple protein found in fish sperm; rich in arginine; simpler in composition than globulin or albumin; counteracts the anticoagulant effect of heparin
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.
FunctionWhen mixed with insulin, protamines slow down the onset and increase the duration of insulin action (see NPH insulin).
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.
HumanThe 2 human protamines are denoted and .
FishExamples of protamines from fish are:
protamine in German: Protamin
protamine in Italian: Protammina
protamine in Japanese: プロタミン
protamine in Polish: Protaminy
protamine in Russian: Протамины