Biochemical and genetic analysis of variant C of caprine α_s2‐casein (Capra hircus)

Abstract

SummaryTwo alleles, A and B, were previously described at the goat αs2‐casein locus. Isoelectric focusing allowed us to subdivide the former one in two new alleles, called A and C. Although αs2‐casein C cannot actually be distinguished from its A counterpart by starch or polyacrylamide gel electrophoresis, it differs from the previous allele by a single substitution Lys (A)/Ile (C) at position 167, which was confirmed at the nucleotide level. The frequencies of the three αs2‐casein alleles A, B and C were estimated to be 0.85, 0.04 and 0.11 in the French dairy breeds ‘Alpine’ and ‘Saanen’.

An investigation on allele frequency at the <i>CSN1S2</i> locus and its relationship with milk parameters in the Sarda goat

“…The allele frequencies recorded for F, A and C were similar to those by Sacchi et al (2005) in several Mediterranean goat breeds. Bouniol et al (1994), in Alpine and Saanen goat breeds, register the highest frequency for the CSN1S2 A allele (0.85) and the lowest for the C allele (0.11). In our study, allele frequencies of CSN1S2 B and E were lower than those evidenced by Sacchi et al (2005) in several Italian goat breeds.…”

“…The CSN1S2 B allele, compared to the A allele, shows a G10A transition at exon 9, which causes a Glu 64 →Lys substitution in the mature protein, while the mutational event characterizing the C variant is a transversion A5T at exon 16, which determines the substitution Lys 167 →Ile (Bouniol et al, 1994). The presence of CSN1S2 A, B and C alleles was investigated by Multiplex Allele Specific PCR (Ramunno et al, 2000), utilizing in the first reaction the two primer pairs: B1X/B1Z and C2X/C2Z, which selectively amplified the CSN1S2 A allele, and in the second PCR reaction the two primer pairs: B1Y/B1Z and C2Y/C2Z, which amplified the CSN1S2 B and C alleles, respectively.…”

Genetic Variability atαs2-caseinGene inGirgentanaDairy Goat Breed

“…So far, eight alleles have been identified, which are associated with different expression levels of as2-casein (CSN1S2) in milk: A, B (Boulanger et al, 1984), C (Bouniol et al, 1994), E (Lagonigro et al, 2001) and F (Ramunno et al, 2001a) are strong alleles associated with a normal content (about 2.5 g/L per allele) of this protein in milk. Intermediate CSN1S2 D allele is associated with a reduced level (about 1.5 g/L per allele), while null CSN1S2 0 allele is associated with non-detectable amount of CSN1S2 in milk (Ramunno et al, 2001a(Ramunno et al, , 2001b.…”

Effects of &lt;italic&gt;CSN1S2&lt;/italic&gt; Genotypes on Economic Traits in Chinese Dairy Goats

“…The A, B, C, E and F alleles are characterized by point mutations related to single amino acid substitutions and associated with a normal amount of αα S2 -casein (2.5 g/L). The CSN1S2 B allele, compared to the A allele, shows a G10A transition at exon 9, which causes a Glu64→Lys substitution in the mature protein, while the mutational events characterizing the C and E variants are substitution A5T (Lys167→Ile) and C83G (Pro193→Arg) at exon 16, respectively (Bouniol et al, 1994). The CSN1S2 F allele is characterized by a G13C transition occurring at exon 3, which results in an amino acid substitution Val7→Ile (Bouniol et al, 1994; Veltri et al, 2000 Ramunno et al, 2001a).…”