Caprine κ-Casein (CSN3) Polymorphism: New Developments in Molecular Knowledge

• Published in: Journal of dairy science Vol. 88; no. 4; pp. 1490 - 1498
• Main Authors: Prinzenberg, E.-M., Gutscher, K., Chessa, S., Caroli, A., Erhardt, G.
• Format: Journal Article
• Language: English
• Published: Savoy, IL Elsevier Inc 01.04.2005; American Dairy Science Association
• Subjects: Alleles; Amino Acid Sequence; Animal productions; Animals; Base Sequence; Biological and medical sciences; Caseins - genetics; Female; Food industries; Fundamental and applied biological sciences. Psychology; goat; Goats - genetics; Milk - chemistry; Milk and cheese industries. Ice creams; Molecular Sequence Data; Mutation; nomenclature; Polymerase Chain Reaction; Polymorphism, Genetic; Polymorphism, Single-Stranded Conformational; single-strand conformation polymorphism; Terrestrial animal productions; Vertebrates; κ-casein polymorphism; nomenclature; ssPCR; IP; CSN3; goat; κ-casein polymorphism; IEF; SSCP; single-strand conformation polymorphism; PCR; Caprine; Knowledge; Milk protein; Vertebrata; Mammalia; Casein; Dairy industry; Development; Artiodactyla; single- strand conformation polymorphism; Ungulata; Polymorphism
• ISSN: 0022-0302; 1525-3198
• DOI: 10.3168/jds.S0022-0302(05)72817-4

A high degree of polymorphism was recently found at the κ-casein (CSN3) locus in the domesticated goat (Capra hircus). In the present study, 2 new patterns previously identified by PCR-single-strand conformation polymorphism analysis (SSCP) were characterized. The allele provisionally named “X” (GenBank Accession no. AY350425) differs from CSN3*C (AF485341) by a (silent) A→G substitution at position 509 of the goat CSN3 reference sequence (X60763). As this newly identified sequence changes the amino acid sequence, and the already known CSN3*C allele (AF485341) has an additional silent mutation, we proposed a change in nomenclature to reflect these changes, indicating the silent mutation with the prime symbol (i.e.,′). The CSN3*M allele (provisionally named “Y”) results in a new protein variant, differing by 2 nonsynonymous mutations from the CSN3*F allele. The new variant is characterized by a G→A transition at nucleotide position 384, resulting in the amino acid exchange Asp90→Asn90, and a C→T transition at position 550, resulting in a Val145→Ala145 substitution. Thus, the number of alleles identified in the domesticated goat has increased to 16, of which 13 are protein variants and 3 are silent mutations, involving a total of 15 polymorphic sites in CSN3 exon 4. Data on the distribution of the main alleles in 7 goat breeds of Europe, West Africa, and the Near East show differences in the occurrence and frequency of the alleles between breeds and geographic origin with the highest number of alleles found in goat breeds from the Near East.