The structural organization of the gene for the human cysteine-proteinase inhibitor cystatin C was studied. Restriction-endonuclease digests of human genomic DNA hybridized with human cystatin C cDNA and genomic probes produced patterns consistent with a single cystatin C gene and, also, the presence of six closely related sequences in the human genome. A 30 kb restriction map covering the genomic region of the cystatin C gene was constructed. The positions of three polymorphic restriction sites, found at examination of digests of genomic DNA from 79 subjects, were localized in the flanking regions of the gene. The gene was cloned and the nucleotide sequence of a 7.3 kb genomic segment was determined, containing the three exons of the cystatin C structural gene as well as 1.0 kb of 5'-flanking and 2.0 kb of 3'-flanking sequences. Northern-blot experiments revealed that the cystatin C gene is expressed in every human tissue examined, including kidney, liver, pancreas, intestine, stomach, antrum, lung and placenta. The highest cystatin C expression was seen in seminal vesicles. The apparently non-tissue-specific expression of this cysteine-proteinase inhibitor gene is discussed with respect to the structure of its 5'-flanking region, which shares several features with those of housekeeping genes.

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The semenogelin I1 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 seinenogelin I1 consists of 683 amino acid residues, has a calculated Mr 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 I1 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.Keywords: semen ; transglutaminase; evolution ; coagulation ; primate.Semen is composed of secretions from the accessory sex glands and epididymal spermatozoa. Newly ejaculated human semen has the structure of a loose gel which liquefies within 5-20 min to release the entrapped spermatozoa. The major gelforming proteins are the closely related semenogelin I and I1 (SgI, SgII), primarily expressed in the seminal vesicles (Lilja and Laurel], 1984;Lilja et al., 1989;Lilja and Lundwall, 1992). The liquefaction of the gel is due to proteolytic degradation of the semenogelins (Sg) by the prostate-secreted protein prostatespecific antigen (PSA;Lilja, 1988). Semen from the rhesus monkey forms a firm gel when fluid from the seminal vesicles is mixed with secretions from the cranial lobe of the prostate (Greer, 1968;van Wagenen, 1936). The liquefaction process seen in man is not observed in the rhesus monkey; instead the spermatozoa are believed to be released by an exudation process that is completed within 40 min (van Pelt and Keyser, 1970). Little is known about the proteins constituting the gel in the rhesus monkey, although immunoreactive material recognized by antibodies raised against human SgI has been found in the seminal vesicles and in the vas deferens (Aumuller et al., 1990).It was recently shown that the genes encoding Sg and other predominant proteins secreted by the seminal vesicles, together with the gene encoding the protease inhibitor skin-derived antileukoproteinase/elafin, constitute a gene family (Lundwall and Lazure, 1995 ;Lundwall, 1996a;Lundwall and Ulvsback, 1996). The genes belonging to this family consist of a characteristic University Hospital, Malmo, S-205 02 Malmo, Sweden three-exon transcription unit in which the nucleotide sequences in the first and the last exon are conserved, whereas the second exon is diss...

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