Description:
<jats:title>Summary</jats:title><jats:p>Prothymosin alpha (PTMA) is a highly acidic, intrinsically disordered protein that was first extracted from rat thymus and characterized as an immunogenic factor but soon detected in a variety of mammalian tissues. The presence of a nuclear localization signal and the adoption of a peculiar random-coil conformation are among the reasons behind its interaction with several molecular partners, hence at this time PTMA is known to be a very conserved and widely expressed molecule, involved in numerous and diverse biological processes. Only few studies have tried to weigh its possible involvement in reproduction, specifically in male gametogenesis: first reports have suggested that PTMA might be associated with the proliferative and early-meiotic phases of mammal spermatogenesis. Some years later, a comparative project on vertebrate spermatogenesis reported the isolation, for the first time, of prothymosin in a non-mammalian species, the amphibian<jats:italic>Pelophylax esculentus</jats:italic>. PTMA transcript and protein are localized in the germinal compartment, from spermatocytes to spermatozoa. A congruent pattern has been highlighted in studies on the fish<jats:italic>Torpedo marmorata</jats:italic>and<jats:italic>Danio rerio</jats:italic>, and in the mammal<jats:italic>Rattus norvegicus</jats:italic>, in which the expression of PTMA has been found in meiotic and post-meiotic germ cells inside testicular cysts and tubules. Moreover, its presence has been confirmed in rat and human spermatozoa (associated with the acrosome); its retention in the apical region of the head after the acrosome reaction revealed a striking conservation of the pattern during phylogenesis and suggested a possible role for the protein in gametogenesis and in fertilization.</jats:p>