Distinct receptors for insulin-like growth factor I in rat renal glomeruli and tubules

Journal Article · Sat Oct 01 00:00:00 EDT 1988 · Am. J. Physiol.; (United States)

OSTI ID:6583571

Pillion, D J; Haskell, J F; Meezan, E

Purified preparations of renal glomeruli and tubules were obtained by a procedure involving perfusion of rat kidneys with magnetic iron oxide particles to selectively separate the iron-containing glomeruli from the nonmagnetic tubules. Detergent-soluble extracts of both renal glomerular and tubular membranes showed high-affinity, specific binding of 125I-labeled insulin-like growth factor I (125I-IGF-I), whereas degradation of this peptide hormone was minimal during a 90-min incubation at 22 degrees C in the presence of 2.5 mM EDTA and 5 mM N-ethylmaleimide. The affinity of these receptors for IGF-I appeared identical in the two types of renal tissue, since 50% inhibition of 125I-IGF-I binding to both glomerular and tubular tissue occurred in the presence of approximately 3 x 10(-9) M unlabeled IGF-I. In contrast, insulin was much less effective at blocking 125I-IGF-I binding to either tissue, with 1 x 10(-6) M insulin required to produce 50% inhibition of binding. Relative to 125I-IGF-I binding, 125I-insulin binding to glomerular and tubular tissue was significantly lower per milligram protein. 125I-IGF-I was specifically cross-linked to a glomerular receptor subunit that migrated as two discrete bands with relative molecular weight (Mr) of 140,000-150,000 on sodium dodecyl sulfate polyacrylamide gels in the presence of 40 mM dithiothreitol. In contrast, 125I-IGF-I was cross-linked to a tubular receptor subunit that migrated as two discrete bands but at a slightly different position, with Mr of 120,000-140,000.

• Research Organization: Univ. of Alabama, Birmingham (USA)
• OSTI ID: 6583571
• Journal Information: Am. J. Physiol.; (United States), Vol. 255
• Country of Publication: United States
• Language: English

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59 BASIC BIOLOGICAL SCIENCES
GROWTH FACTORS
RECEPTORS
BIOCHEMICAL REACTION KINETICS
AUTORADIOGRAPHY
CELL MEMBRANES
ELECTROPHORESIS
INSULIN
IODINE 125
KIDNEYS
MOLECULAR WEIGHT
PERFUSED ORGANS
RATS
ANIMALS
BETA DECAY RADIOISOTOPES
BODY
CELL CONSTITUENTS
DAYS LIVING RADIOISOTOPES
ELECTRON CAPTURE RADIOISOTOPES
HORMONES
INTERMEDIATE MASS NUCLEI
IODINE ISOTOPES
ISOTOPES
KINETICS
MAMMALS
MEMBRANE PROTEINS
MEMBRANES
MITOGENS
NUCLEI
ODD-EVEN NUCLEI
ORGANIC COMPOUNDS
ORGANS
PEPTIDE HORMONES
PROTEINS
RADIOISOTOPES
REACTION KINETICS
RODENTS
VERTEBRATES
550201* - Biochemistry- Tracer Techniques