Characterization and cloning of the mRNAs specific for the lactating mouse mammary gland.
We have characterized and cloned the lactation-specific mRNAs of mouse mammary glands. The group of eight milk-protein-specific mRNAs were identified (a) by size and antigenic properties of their translation products in vitro and (b) by characterization of their respective cDNA clones. Two alpha-caseins (43 kDa and 39 kDa) are encoded by mRNAs of 1600 nucleotides and two beta-caseins (26 kDa) are encoded by mRNAs of 1450 nucleotides in length. Three smaller caseins, gamma-casein (23.7 kDa), delta-casein (21 kDa) and epsilon-casein (14.5 kDa) are synthesized by mRNAs of 880, 1150 and 860 nucleotides. Beside these casein mRNAs a mammary specific 620 nucleotide mRNA codes for a novel acidic whey protein (13.7 kDa). cDNA clones corresponding to the mRNAs for the lactation-specific proteins have been isolated from a mammary-specific cDNA library. Cloned alpha-casein cDNA hybridizes to both alpha-casein specific mRNAs and cloned beta-casein cDNAs hybridize with both beta-casein specific mRNAs. By RNA blot analysis we show that the cloned cDNAs for mouse alpha-casein, beta-casein, gamma-casein and epsilon-casein and the acidic whey protein cross-hybridize with mRNAs of the rat, demonstrating partial sequence homology between the corresponding mRNAs of those species.
D000818:Animals; D003001:Cloning, Molecular; D004247:DNA; D004591:Electrophoresis, Polyacrylamide Gel; D005260:Female; D007120:Immunochemistry; D007774:Lactation; D008321:Mammary Glands, Animal / Q000378:metabolism*; D051379:Mice; D008894:Milk Proteins / Q000096:biosynthesis*; D011247:Pregnancy; D014176:Protein Biosynthesis; D012333:RNA, Messenger; D051381:Rats
D008894:Milk Proteins; D012333:RNA, Messenger; D004247:DNA