Molecular cloning and characterization of a mono(ADP-ribosyl)transferase from human testis

A human homologue of the rodent T cell mono(ADP-ribosyl)transferase RT6 mRNA was identified by a systematic partial sequencing of human testis transcripts. This messenger encodes for a precursor protein of 367 aa (MW: 41.5 kDa) which exhibits a peptide signal, consensus domains for mono(ADP-ribosyl)transferase and a C terminal part which contains three repeated motives (GEKNQKLEDH) and a region characteristic of glycophosphatidyl inositol anchored proteins. This mRNA is transcribed from a gene localized in 4q13-q21. Surprisingly, it is not expressed in human white blood cells but it exhibits a very specific testis expression in which it is likely to correspond to a new ADP-ribosyl transferase.