PROSITE documentation PDOC00749

Nuclear transition protein 2 signatures

In mammals, the second stage of spermatogenesis is characterized by the conversion of nucleosomal chromatin to the compact, nonnucleosomal and transcriptionally inactive form found in the sperm nucleus. This condensation is associated with a double-protein transition. The first transition corresponds to the replacement of histones by several spermatid-specific proteins, also called transition proteins, which are themselves replaced by protamines during the second transition.

Nuclear transition protein 2 (TP2) is one of those spermatid-specific proteins. TP2 is a basic, zinc-binding protein [1] of 116 to 137 amino-acid residues. Structurally, TP2 consists of three distinct parts: a conserved serine-rich N-terminal domain of about 25 residues, a variable central domain of 20 to 50 residues which contains cysteine residues, and a conserved C-terminal domain of about 70 residues rich in lysines and arginines.

We developed two signature patterns for TP2: one located in the N-terminal domain, the other in the C-terminal.