Casein and α-lactalbumin messenger RNAs during the development of mouse mammary gland
1980; Elsevier BV; Volume: 78; Issue: 2 Linguagem: Inglês
10.1016/0012-1606(80)90334-6
ISSN1095-564X
AutoresToshiyuki Takemoto, Yasunori Nagamatsu, Takami Oka,
Tópico(s)Infant Nutrition and Health
ResumoMessenger RNAs for the milk proteins, casein and α-lactalbumin, were isolated and partially purified from lactating mouse mammary glands by oligo(dT)cellulose chromatography followed by sucrose density gradient centrifugation. The translation of poly(A)+ mRNA in a wheat germ cell-free system yielded three casein polypeptides and a putative precursor form of α-lactalbumin which were precipitated by specific antibodies and characterized by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The casein polypeptides synthesized in vitro had a molecular weight that was no greater than that of the caseins in mouse milk. The presence of individual casein mRNAs coding for these polypeptides was demonstrated by the translation of various fractions of mRNA obtained by sucrose density gradient centrifugation of poly(A)+ mRNA. Casein mRNA activity increased about 250-fold between midpregnancy and the 10th–12th days of lactation, amounting to 50–60% of the total mRNA activity in that tissue. A similar study of α-lactalbumin mRNA showed an increase during lactation amounting to 0.2–0.4% of the total mRNA activity, which corresponds to the percentage of α-lactalbumin in total mouse milk protein.
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