A novel gene family encoding proteins with highly differing structure because of a rapidly evolving exon

Abstract

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 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.

The Cloning of a Rapidly Evolving Seminal‐Vesicle‐Transcribed Gene Encoding the Major Clot‐Forming Protein of Mouse Semen

“…6A), a similarity that extends for the whole of the available rat SVS I1 sequence. As previously indicated [17], the sequence of the rat SVS 11 gene is probably incomplete and lacks the sequence of the third exon. In Fig.…”

“…The probe that encodes the second exon of the rat SVS I1 gene has previously been shown to detect hybridizing material in mouse DNA [17]. The use of the same conditions to probe the mouse genomic library, yielded nine hybridizing clones among the 1 X 1 Oh recombinants screened.…”

“…The mouse semenoclotin gene is likely to be a new member of the recently described REST gene family, encompassing several seminal-vesicle-transcribed genes [17]. To determine the extent of conserved nucleotides by comparing to other members of the gene family, relatively large regions of the DNA flanking the gene were sequenced.…”

“…A genoinic library, constructed in AFIX I1 using DNA from the mouse strain 129, was purchased from Stratagene. l X l O6 recombinants of the library were screened by standard procedures [I81 using as a probe the previously cloned fragment of the rat SVS 11 gene that was generated by polymerase chain reaction [17]. Phage stocks were made from the purified clones and stored at -80°C with 7% dimethyl sulfoxide added.…”

The semenogelins: proteins with functions beyond reproduction?

“…Thus, the expressed proteins in this family show wide variation in primary structure. Accordingly, it seems that they have evolved rapidly [11,12], which would explain why semenogelins I and II are apparently found solely in primates, and, even within that taxonomic group, there are obvious interspecies differences in the molecules [13,14]. Rats and mice also express seminal vesicle proteins that belong to the same family and show high sequence similarity in the products encoded by exons one and three, whereas the translated middle exon exhibits little similarity to the primate counterpart [12].…”