Regulation of casein synthesis in the rabbit mammary gland.  Titration of mRNA activity for casein under prolactin and progesterone treatments.
Total polysomal RNA or poly(A)-containing RNA isolated from membrane-bound polysomes of normal lactating rabbits directed the synthesis of casein in a reticulocyte lysate. Casein was identified by immunoprecipitation followed by SDS-polyacrylamide gel electrophoresis of the immunoprecipitate. The poly(A)-containing RNA was heterogeneous with one major peak corresponding to a 12-S sedimentation coefficient as determined by polyacrylamide gel electrophoresis. Using the same procedure, mRNAs isolated from the non-secreting tissue of pseudopregnant rabbits were found not to contain the 12-S peak and were unable to direct the synthesis of casein in vitro. Prolactin injected into pseudopregnant rabbits induced the synthesis of proteins immunoprecipitable by anti-casein anti-serum and induced the simultaneous appearance of the 12-S mRNA. Progesterone injected with prolactin prevented the induction of casein synthesis and the appearance of mRNA for casein. A close relationship was established between the ability of the tissue to synthesize immunoprecipitable casein and the corresponding mRNA content of polysomes.
D000818:Animals; D002364:Caseins / Q000096:biosynthesis* / Q000276:immunology; D005260:Female; D007532:Isoleucine / Q000378:metabolism; D007774:Lactation / Q000187:drug effects; D008321:Mammary Glands, Animal / Q000187:drug effects / Q000378:metabolism*; D011132:Polyribosomes / Q000187:drug effects / Q000378:metabolism; D011233:Precipitin Tests; D011247:Pregnancy; D011374:Progesterone / Q000494:pharmacology*; D011388:Prolactin / Q000494:pharmacology*; D011392:Proline / Q000378:metabolism; D014176:Protein Biosynthesis / Q000187:drug effects*; D011555:Pseudopregnancy; D012333:RNA, Messenger / Q000378:metabolism*; D011817:Rabbits; D012156:Reticulocytes / Q000378:metabolism; D012756:Sheep; D013997:Time Factors
D002364:Caseins; D012333:RNA, Messenger; D007532:Isoleucine; D011374:Progesterone; D011388:Prolactin; D011392:Proline