Role of mammary casein kinase in the phosphorylation of milk proteins.
Casein kinase from lactating bovine mammary gland catalyses the transfer of the terminal phosphoryl group of ATP to specific serine residues in dephosphorylated caseins. Best substrates for casein kinase are the dephosphorylated proteins (bovine alpha S1- and beta-caseins and pepsin), unphosphorylated human beta-casein and the dephosphorylated peptide (residues 1-25) from bovine beta-casein. Results obtained with bovine and human beta-caseins indicate that the two serines underlined in the cluster Ser-Leu-Ser-Ser-Ser are particularly susceptible to the action of casein kinase. Since a similar sequence is found in dephosphorylated alpha S1-casein, it is probable that serines in this region of alpha S1-casein are also phosphorylated. The results support the concept that certain serines in casein are particularly susceptible to phosphorylation by casein kinase.
D000595:Amino Acid Sequence; D000818:Animals; D002364:Caseins; D002417:Cattle; D005260:Female; D014644:Genetic Variation; D006801:Humans; D007774:Lactation; D008321:Mammary Glands, Animal / Q000201:enzymology*; D008894:Milk Proteins / Q000378:metabolism*; D010766:Phosphorylation; D011247:Pregnancy; D011494:Protein Kinases / Q000378:metabolism*
D002364:Caseins; D008894:Milk Proteins; D011494:Protein Kinases