Studies were carried out to investigate the mechanism by which prolactin stimulates
casein synthesis in cultured mouse mammary tissues. The onset of the prolactin stimulation
of casein synthesis occurs 8-10 hours after prolactin addition to cultured tissues;
a maximum effect is evoked by 16 hours. A similar time-course of response to prolactin
was observed when the tissue accumulation of the mRNA for β-casein was determined.
At 16 hours, however, prolactin had no effect on tissue-specific casein kinase activity
which is associated with the Golgi apparatus. These studies suggest that the tissue
content of casein mRNA is causally related to the onset of the prolactin stimulation
of casein synthesis in cultured mouse tissues. In contrast, the activity of the kinase
that catalyzes the phosphorylation of the caseins is not altered by prolactin and
thus apparently is not a contributing factor to the early prolactin effect on casein
synthesis.
Casein Kinase - Galactosyl Transferase - Casein Synthesis - Casein mRNA - Mammary
Gland - Prolactin
