title: Heterogeneity of caprine beta-casein elucidated by RP-HPLC/MS: genetic variants and phosphorylations.
abstract: Casein variants occurring in milks from goats homozygous at the alpha(s1)-Cn locus were separated and identified by an RP-HPLC/ESI-MS method. Preferential haplotypes arose as well as some particularities in posttranslational modifications. A new variant of caprine beta-Cn, named C, as well as the phosphorylations pattern of the protein were characterized by the combined use of peptide mass fingerprinting and sequencing by tandem mass spectrometry. The molecular mass of the new variant in its 6P form was measured as 23854 Da and it differs in a mono amino acid substitution, A177 --> V177, from the variant A. The phosphorylation pattern of caprine beta-Cn is homologous to bovine beta-Cn concerning the 5P located on Ser15, 17, 18, 19, 35 but it presents a specific additional phosphorylation site on Thr12 that is comparable to human beta-Cn phosphorylation located on Thr3.
authors.affiliation: INRA, Laboratoire de Recherche de Technologie Laitière, 35042 Rennes cedex, France.
authors.forename: Carole
authors.initials: C
authors.lastname: Neveu
authors.forename: Daniel
authors.initials: D
authors.lastname: Mollé
authors.forename: Javier
authors.initials: J
authors.lastname: Moreno
authors.forename: Patrice
authors.initials: P
authors.lastname: Martin
authors.forename: Joëlle
authors.initials: J
authors.lastname: Léonil
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D002364:Caseins / Q000737:chemistry* / Q000235:genetics / Q000302:isolation & purification; D002417:Cattle; D002851:Chromatography, High Pressure Liquid / Q000379:methods*; D005838:Genotype; D006041:Goats; D006720:Homozygote; D006801:Humans; D013058:Mass Spectrometry / Q000379:methods*; D008969:Molecular Sequence Data; D010446:Peptide Fragments / Q000737:chemistry; D010766:Phosphorylation; D011110:Polymorphism, Genetic; D013912:Threonine / Q000737:chemistry; D013997:Time Factors; D014357:Trypsin / Q000494:pharmacology
chemical_list: D002364:Caseins; D010446:Peptide Fragments; D013912:Threonine; D014357:Trypsin