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 CSN3H and 1), and the third (named CSN3A1) 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 CSN3H and to a Ser/Ala substitution in position 104 of the deduced amino acid sequence of CSN31 (GenBank accession numbers AF105260 and AF121023) compared to CSN3A. In CSN3A1, a silent mutation in the third codon position of Pro150 was found (GenBank accession number AF092513).