Post-translational Modification of κ-Casein in the Golgi Apparatus of Mid-lactating Mammary Glands from Rat and Cow

Takeuchi, Makoto; Tsuda, Eisuke; Yoshikawa, Masaaki; Sasaki, Ryuzo; Chiba, Hideo

doi:10.1080/00021369.1984.10866572

Cited by 1 publication

(2 citation statements)

References 8 publications

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“…A total of nine different fractions for whole K-casein was reported by Takeuchi et al (1984), which is in good agreement with the number of bands in Fig. 1.…”

Section: Discussion K-casein Fractionation and Classification Of Componentssupporting

confidence: 86%

“…According to Takeuchi et al (1984) the following sequence takes place in the lactating cell of the Golgi apparatus: phosphorylation of casein, assembly of casein micelles, glycosylation of K-casein on the surface of the micelle. Since we found only multiply phosphorylated fractions without carbohydrate, one could infer that phosphorylation of Ser-1 27 inhibits glycosylation in vivo.…”

Section: Discussion K-casein Fractionation and Classification Of Componentsmentioning

confidence: 99%

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Characterization of bovine κ-casein fractions and the kinetics of chymosin-induced macropeptide release from carbohydrate-free and carbohydrate-containing fractions determined by high-performance gel-permeation chromatography

Vreeman¹,

Visser²,

Slangen³

et al. 1986

Biochemical Journal

135

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Bovine kappa-casein was fractionated at pH 8.0 on DEAE-Sepharose with an NaCl gradient, followed by DEAE-cellulose chromatography using a decreasing pH gradient from pH 6.0 to 4.5. At least ten components could be identified, each differing in N-acetylneuraminic acid (NeuAc) and/or phosphorus content. Two components appeared to be multiply-phosphorylated, but did not contain NeuAc. The possible significance of this finding in relation to the mode of phosphorylation and glycosylation in vivo is discussed. A carbohydrate-free fraction as well as two NeuAc-containing fractions were compared in their substrate behaviour towards the action of the milk-clotting enzyme chymosin at pH 6.6 and 30 degrees C. To this end the trichloroacetic acid-soluble reaction products were analysed by high-performance gel-permeation chromatography. In order of increasing carbohydrate content the kcat. values found ranged from 40 to 25 s-1 and the Km values from 9 to 3 microM; the overall substrate properties of these components as reflected by the kinetic parameter kcat./Km ranged from 5 to 8 microM-1 X S-1. Irreversible polymerization of the carbohydrate-free fraction brought about a more-than-2-fold increase in Km, the kcat. value remaining virtually constant. The kcat./Km found for the cleavage of whole kappa-casein at pH 6.6 was of the same magnitude as the kcat./Km found for the polymerized carbohydrate-free fraction (i.e. about 3 microM-1 X S-1). No indication of substrate inhibition was found for the carbohydrate-free fraction.

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“…A total of nine different fractions for whole K-casein was reported by Takeuchi et al (1984), which is in good agreement with the number of bands in Fig. 1.…”

Section: Discussion K-casein Fractionation and Classification Of Componentssupporting

confidence: 86%

Section: Discussion K-casein Fractionation and Classification Of Componentsmentioning

confidence: 99%

Characterization of bovine κ-casein fractions and the kinetics of chymosin-induced macropeptide release from carbohydrate-free and carbohydrate-containing fractions determined by high-performance gel-permeation chromatography

Vreeman¹,

Visser²,

Slangen³

et al. 1986

Biochemical Journal

135

View full text Add to dashboard Cite

show abstract

Post-translational Modification of κ-Casein in the Golgi Apparatus of Mid-lactating Mammary Glands from Rat and Cow

Cited by 1 publication

References 8 publications

Characterization of bovine κ-casein fractions and the kinetics of chymosin-induced macropeptide release from carbohydrate-free and carbohydrate-containing fractions determined by high-performance gel-permeation chromatography

Characterization of bovine κ-casein fractions and the kinetics of chymosin-induced macropeptide release from carbohydrate-free and carbohydrate-containing fractions determined by high-performance gel-permeation chromatography

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