Despite vast differences in primary structure, it is here shown that several predominant semen proteins are encoded by genes that belongs to a common family. Members have their transcription unit split into three exons: the first encoding the signal peptide, the second the secreted protein, while the third exon solely consists of 3′ non-translated nucleotides. The first and and the third exon are conserved between members, but the second exon is not. The genes for human semenogelins I and II, rat SVSII, SVSIV, SVSV and guinea pig GP1 and GP2 belong to this gene family.
