Developmental expression of the tissue insulin-like growth factor II/mannose 6-phosphate receptor in the rat. Measurement by quantitative immunoblotting.
We used quantitative immunoblotting to measure the total tissue insulin-like growth factor II/mannose 6-phosphate (IGF-II/Man-6-P) receptor in the rat. Whole embryos (6-15 days of gestation) and tissues from 16- and 20-day-old fetal and 5-, 10-, 20-, and 40-day-old postnatal rats were placed in liquid nitrogen, extracted with 2% Triton X-100, and boiled in 2% sodium dodecyl sulfate. The extracts were analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis together with aliquots of a highly purified rat IGF-II/Man-6-P receptor standard. The protein bands were transferred from the gel to nitrocellulose sheets by electroelution. The nitrocellulose sheets were incubated with a specific IGF-II/Man-6-P receptor antiserum (3637). The immunoblots were developed with 125I-protein A and an immunoperoxidase stain. Stained areas were cut from the immunoblots, and radioactivity was measured in a gamma-counter. IGF-II/Man-6-P receptor levels were high in fetal tissues and in most tissues declined dramatically in late gestation and/or in the early postnatal period. Concentrations in 16-day-old fetal tissues, expressed as percent of total protein in the extract, were: heart, 1.7; placenta, 1.0; lung, 0.7; intestine, 0.7; muscle, 0.5; kidney, 0.5; liver, 0.3; and brain, 0.1. In whole embryos (6-15 days of gestation), the IGF-II/Man-6-P receptor ranged between 0.1 and 0.4% of total protein in the extract. The IGF-II/Man-6-P receptor size varied within approximately 20 kDa among different tissues and also varied with developmental age in the same tissue. We conclude that the IGF-II/Man-6-P receptor is a major cellular protein in some fetal tissues and that the developmental pattern of receptor expression suggests that the receptor plays an important role in fetal growth and development.
Sklar
M M
MM
Metabolism Branch, National Cancer Institute, Bethesda, Maryland 20892.
Kiess
W
W
Thomas
C L
CL
Nissley
S P
SP
D000375:Aging / Q000378:metabolism*; D000818:Animals; D005314:Embryonic and Fetal Development; D005333:Fetus / Q000378:metabolism*; D006600:Hexosephosphates / Q000378:metabolism*; D015151:Immunoblotting; D007335:Insulin-Like Growth Factor II / Q000378:metabolism*; D008360:Mannosephosphates / Q000378:metabolism*; D009928:Organ Specificity; D051381:Rats; D011919:Rats, Inbred Strains; D017527:Receptor, IGF Type 2; D011956:Receptors, Cell Surface / Q000032:analysis / Q000096:biosynthesis*; D017451:Receptors, Somatomedin; D013002:Somatomedins / Q000378:metabolism*
D006600:Hexosephosphates; D008360:Mannosephosphates; D017527:Receptor, IGF Type 2; D011956:Receptors, Cell Surface; D017451:Receptors, Somatomedin; D013002:Somatomedins; D007335:Insulin-Like Growth Factor II