RESUMO
<p><b>AIM</b>To investigate wether the corresponding protein of mono-ADP-ribosyltransferase 3 (ART3) mRNA is expressed in human testes and, if so, whether the expression is cell type-specific.</p><p><b>METHODS</b>ART3 mRNA was determined in human testes and sperm by reverse transcription-polymerase chain reaction (RT-PCR). The glycosyl-phosphatidylinositol linkage of ART3 was shown by treating ART3-transfected HEK-293-T cells with phospholipase C. Fluorescent activated cell sorter (FACS)-analyses were used to detect ART3 on mature spermatozoa and immunohistological studies to detect the protein in testes.</p><p><b>RESULTS</b>ART3 protein was shown to be present in testes. It was found on spermatocytes only. It was absent from spermatogonia, spermatids and spermatozoa. The absence of ART3 from spermatozoa was confirmed by FACS-analysis. ART3 protein was detected neither within a seminoma nor on Leydig cells.</p><p><b>CONCLUSION</b>Here we show for the first time that ART3 protein is expressed in testes in particular on spermatocytes, indicating that ART3 exerts a specific function only required at a particular stage of spermatogenesis.</p>