Functional properties of an isolated. cap alpha beta. heterodimeric human placenta insulin-like growth factor 1 receptor complex

Journal Article · Tue May 03 00:00:00 EDT 1988 · Biochemistry; (United States)

OSTI ID:7143765

Feltz, S M; Swanson, M L; Wemmie, J A; Pessin, J E

Treatment of human placenta membranes at pH 8.5 in the presence of 2.0 mM dithiothreitol (DTT) for 5 min, followed by the simultaneous removal of the DTT and pH adjustment of pH 7.6, resulted in the formation of a functional ..cap alpha beta.. heterodimeric insulin-like growth factor 1 (IGF-1) receptor complex from the native ..cap alpha../sub 2/..beta../sub 2/ heterotetrameric disulfide-linked state. The membrane-bound ..cap alpha beta.. heterodimeric complex displayed similar curvilinear /sup 125/I-IGF-1 equilibrium binding compared to the ..cap alpha../sub 2/..beta../sub 2/ heterotetrameric complex. /sup 125/I-IGF-1 binding to both the isolated ..cap alpha../sub 2/..beta../sub 2/ heterotetrameric and ..cap alpha beta.. heterodimeric complexes demonstrated a marked straightening of the Scatchard plots, compared to the placenta membrane-bound IGF-1 receptors, with a 2-fold increase in the high-affinity binding component. IGF-1 stimulation of IGF-1 receptor autophosphorylation indicated that the ligand-dependent activation of ..cap alpha beta.. heterodimeric protein kinase activity occurred concomitant with the reassociation into a covalent ..cap alpha../sub 2/..beta../sub 2/ heterotetrameric state. These data demonstrate that (i) a combination of alkaline pH and DTT treatment of human placenta membranes results in the formation of an ..cap alpha beta.. heterodimeric IGF-1 receptor complex, (ii) unlike the insulin receptor, high-affinity homogeneous IGF-1 binding occurs in both the ..cap alpha../sub 2/..beta../sub 2/ heterotetrameric and ..cap alpha beta.. heterodimeric complexes, and (iii) IGF-1-dependent autophosphorylation of the ..cap alpha beta.. heterodimeric IGF-1 receptor complex correlates wit an IGF-1 dependent covalent reassociation into an ..cap alpha../sub 2/..beta../sub 2/ heterotetrameric disulfide-linked state.

• Research Organization: Univ. of Iowa, Iowa City (USA)
• OSTI ID: 7143765
• Journal Information: Biochemistry; (United States), Vol. 27:9
• Country of Publication: United States
• Language: English

Related Subjects

59 BASIC BIOLOGICAL SCIENCES
GROWTH FACTORS
BIOCHEMICAL REACTION KINETICS
CONFIGURATION INTERACTION
INSULIN
RECEPTORS
ATP
COMPLEXES
ELECTROPHORESIS
ENZYME INHIBITORS
IODINE 125
MAN
PHOSPHORUS 32
PHOSPHORYLATION
PLACENTA
ANIMALS
BETA DECAY RADIOISOTOPES
BETA-MINUS DECAY RADIOISOTOPES
CHEMICAL REACTIONS
DAYS LIVING RADIOISOTOPES
ELECTRON CAPTURE RADIOISOTOPES
FETAL MEMBRANES
HORMONES
INTERMEDIATE MASS NUCLEI
IODINE ISOTOPES
ISOTOPES
KINETICS
LIGHT NUCLEI
MAMMALS
MEMBRANE PROTEINS
MEMBRANES
MITOGENS
NUCLEI
NUCLEOTIDES
ODD-EVEN NUCLEI
ODD-ODD NUCLEI
ORGANIC COMPOUNDS
PEPTIDE HORMONES
PHOSPHORUS ISOTOPES
PRIMATES
PROTEINS
RADIOISOTOPES
REACTION KINETICS
VERTEBRATES
550201* - Biochemistry- Tracer Techniques