Fast protein liquid chromatography (FPLC) of the .kappa.-casein from bovine casein micelles of different sizes is used to demonstrate that the proportions of glycosylated and non-glycosylated forms of .kappa.-casein do not vary with micellar size. Apparently, glycosylated .kappa.-casein is distributed similarly to unglycosylated .kappa.-casein within the micellar structure.