Cloning of the semenogelin II gene of the rhesus monkey. Duplications of 360 bp extend the coding region in man, rhesus monkey and baboon.

The semenogelin II gene from the rhesus monkey has been cloned and characterized. The transcription unit is split into three exons of 97, 2086 and 124 bp, with two intervening introns of 241 bp and 862 bp. The first exon codes for a 23-amino-acid signal peptide and the two amino-terminal residues of the secreted protein. The second exon codes for the rest of the mature protein, and the third exon contains non-coding nucleotides only. Secreted rhesus monkey semenogelin II consists of 683 amino acid residues, has a calculated M(r) of 77362, is devoid of Cys and Met, and displays a highly repetitive structure composed of ten 60-amino-acid repeats. Hybridization with genomic DNA showed that the semenogelin II gene of man, rhesus monkey and baboon has evolved through extension of the coding region with 360-bp segments. In contrast, the length of the semenogelin I gene of these species appears to be conserved. The two genes are also present in some New World monkeys, as was revealed by hybridization with genomic DNA from the marmoset. However, another New World monkey, the cotton-top tamarin, carries only one semenogelin gene, but also has a gene that is similar to the mouse semenoclotin gene.