Sequence of caprine alpha s1-casein and characterization of those of its genetic variants which are synthesized at a high level, alpha s1-CnA, B and C.
The sequence of caprine alpha s1-casein (199 residues) was established. The peptide chain has the same length as, and shows a 88% degree of identity with, its bovine counterpart. With the ovine alpha s1-casein, the sequence of which was deduced from that of its mRNA, the degree of identity is 97%, counting as one difference a deletion of eight residues in the ovine protein. The differences between the three genetic variants associated with a high alpha s1-casein content in milk are simple substitutions. Variant alpha s1-CnA differs from variant alpha s1-CnB by two substitutions, 16 Leu (A)----Pro (B) and 77 Gln (A)----Glu (B), the latter inducing the appearance of a phosphate group on 75 Ser. Variant alpha s1-CnC differs from alpha s1-CnB by three substitutions, 8 His (B)----Ile (C), 100 Arg (B)----Lys (C) and 195 Thr (B)----Ala (C). The original type of caprine alpha s1-casein could be another hypothetical genetic variant, having the same electrophoretic mobility as alpha s1-CnB.
Brignon
G
G
Laboratoire de Biochimie et Technologie laitières, INRA, Jouy-en-Josas, France.
Mahé
M F
MF
Grosclaude
F
F
Ribadeau-Dumas
B
B
D000595:Amino Acid Sequence; D000596:Amino Acids / Q000032:analysis; D000818:Animals; D002364:Caseins / Q000096:biosynthesis / Q000235:genetics*; D002417:Cattle; D002851:Chromatography, High Pressure Liquid; D014644:Genetic Variation; D006041:Goats; D008969:Molecular Sequence Data; D010766:Phosphorylation; D012333:RNA, Messenger / Q000235:genetics; D012756:Sheep
D000596:Amino Acids; D002364:Caseins; D012333:RNA, Messenger