AJP - Endocrinology and Metabolism, Vol 270, Issue 2 E244-E250, Copyright © 1996 by American Physiological Society
Multiple forms of 6-phosphofructo-2-kinase/fructose-2,6-bisphosphatase are expressed in perinatal rat liver
M. Casado, L. Bosca and P. Martin-Sanz
Facultad de Farmacia, Instituto de Bioquimica, Consejo Superior de Investigaciones Cientificas-Universidad Complutense, Madrid, Spain.
Fetal rat liver expresses a
6-phosphofructo-2-kinase/fructose-2,6-bisphosphatase (PFK-2/Fru-2,6-Pase2)
form that differs from the adult liver enzyme in the inhibition by
phosphorylation by the adenosine 3',5'-cyclic monophosphate-dependent
protein kinase and in the recognition by an antibody specific for the
NH2-terminal domain of the adult liver enzyme. Northern blot analysis shows
that fetal hepatocytes contain a species of mRNA that is 2.2 kb in size and
that exhibits the maximal levels after delivery. PFK-2/Fru-2,6-Pase2 mRNA
analysis using a sensitive ribonuclease protection assay reveals the
presence of nearly similar amounts of adult liver-specific and skeletal
muscle-specific mRNA in fetal liver and hepatocytes during the last days of
gestation, as well as a 233-bp protected fragment present in fetal liver.
These results were confirmed by polymerase chain reaction using specific
oligonucleotide pairs. Primer extension of fetal liver cDNA suggests the
presence of two initiation sites of transcription. Analysis of the adult
liver PFK-2/Fru-2,6-Pase2 protein during the perinatal transition using a
specific antibody shows a marked accumulation of this form immediately
after birth.
