SSCP analysis at the bovine CSN3 locus discriminates six alleles corresponding to known protein variants (A, B, C, E, F, G) and three new DNA polymorphisms (H, I, A1).

A high resolution SSCP protocol was developed for simultaneous discrimination of the known CSN3 alleles A, B, C, E, F and G. Furthermore, three new DNA polymorphisms were identified in different Bos taurus and Bos indicus breeds or crosses. Mendelian segregation was shown for two of these polymorphisms (named CSN3*H and 1), and the third (named CSN3*A1) was found in unrelated animals, thus indicating the presence of three additional alleles at the bovine CSN3 locus. DNA sequencing revealed single mutations that led to a Thr/Ile substitution in amino acid position 135 for CSN3*H and to a Ser/Ala substitution in position 104 of the deduced amino acid sequence of CSN3*1 (GenBank accession numbers AF105260 and AF121023) compared to CSN3*A. In CSN3*A1, a silent mutation in the third codon position of Pro150 was found (GenBank accession number AF092513).