Human beta-casein.
Human beta-casein occurs in multiphosphorylated forms having the same amino acid composition but with 0-5 phosphate groups/molecule. Sequence analysis was used to determine whether each of the phosphorylated forms is a mixture of species having a certain number of phosphate groups randomly distributed or whether each form contains phosphate groups on specific seryl or threonyl residues. It was found that forms containing 2, 4 and 5 phosphate groups/molecule are homogeneous with respect to their phosphorylation sites. The monophosphorylated form, however, is a mixture of equal amounts of species phosphorylated at residues 9 or 10.
D000595:Amino Acid Sequence; D000596:Amino Acids / Q000032:analysis; D002364:Caseins; D005260:Female; D006801:Humans; D008895:Milk, Human / Q000032:analysis*; D009943:Organophosphorus Compounds / Q000032:analysis; D010766:Phosphorylation; D011247:Pregnancy; D012694:Serine
D000596:Amino Acids; D002364:Caseins; D009943:Organophosphorus Compounds; D012694:Serine