Background:
Transition nuclear proteins (TNP1 and TNP2) are the major nuclear proteins that replace somatic histones during spermatogenesis. TNPs are required for normal chromatin condensation and functional sperm development, spermatogenesis was found to be compromised in both Tnp1 and Tnp2 null mice. TNP1, or TP1, localized in nucleus, is a spermatid-specific product of the haploid genome which replaces histone and is itself replaced in the mature sperm by the protamines. Recently, TNP-1 was used as a germ cell marker in condensing spermatids.