Alteration of 6-phosphofructo-1-kinase subunit protein, synthesis rates, and mRNA during rat neonatal development.

For the three 6-phosphofructo-1-kinase (PFK) subunits in heart, skeletal muscle, liver and kidney, developmentally-associated changes in protein, mRNA and apparent synthesis rates were observed. During neonatal maturation, all three phenomena for the M-type in heart and skeletal muscle exhibited large increases. Also, during neonatal development, the L-type and C-type subunits were unaffected in heart but disappeared from skeletal muscle. In the newborn liver and kidney, the amounts of each type of PFK subunit protein were nearly identical. During neonatal development, the levels of all three PFK subunit proteins in kidney increased more than twofold; and this was associated with a similar increase in apparent subunit synthesis rates and mRNA levels. During liver neonatal development, the L-type subunit protein, synthesis and mRNA levels also increased more than twofold. However, during hepatic maturation, M-type subunit protein, synthesis and mRNA levels were unchanged and apparently unaffected. The C-type subunit protein during neonatal liver development decreased approximately 80% as did its apparent synthesis rate. These data suggest that regulation of the alteration of the PFK subunit proteins during neonatal maturation can vary among these tissues and is not the same for each subunit type. Different mechanisms, such as transcription, translation, and mRNA stability could be involved.