Insulin receptors in developing rat liver. Receptor autophosphorylation and phosphorylation of the endogenous substrate pp120/HA4 (ecto-ATPase) in fetal and neonatal liver.
The development of insulin receptors and insulin-stimulated receptor autophosphorylation were studied in livers of prenatal and neonatal rats. Insulin receptors were present in mid-gestation, as early as day 14 in fetal development (full term is 22 days in the rat), with ligand-activated receptor kinase present. In contrast, insulin-stimulated phosphorylation of a Mr 120 kd glycoprotein derived from rat liver membranes, known as pp120/HA4 and more recently identified as ecto-ATPase, was not observed in fetal liver until day 17 of gestation. Thereafter, phosphorylation of pp120/HA4 increased throughout late gestation. The data suggest that maturation of the insulin receptor kinase occurs soon after initial appearance of the receptor in mid-gestation, but insulin-stimulated phosphorylation of endogenous substrate(s) is dependent on the appearance of specific substrates, such as pp120/HA4.
Margolis
R N
RN
Department of Anatomy and Oncology, Howard University.
Tanner
K
K
Seminara
D
D
Taylor
S I
SI
D000251:Adenosine Triphosphatases / Q000378:metabolism*; D000818:Animals; D000831:Animals, Newborn / Q000378:metabolism; D004586:Electrophoresis; D005333:Fetus / Q000378:metabolism; D007328:Insulin / Q000378:metabolism; D007334:Insulin-Like Growth Factor I / Q000502:physiology; D008099:Liver / Q000254:growth & development* / Q000378:metabolism; D010766:Phosphorylation; D051381:Rats; D011919:Rats, Inbred Strains; D011972:Receptor, Insulin / Q000378:metabolism*
D007328:Insulin; D007334:Insulin-Like Growth Factor I; D011972:Receptor, Insulin; D000251:Adenosine Triphosphatases; C027201:ectoATPase