Separation and characterization of three insulin receptor species that differ in subunit composition

Journal Article · Tue Jul 26 04:00:00 EDT 1988 · Biochemistry; (United States)

DOI:https://doi.org/10.1021/bi00415a045· OSTI ID:7002616

O'Hare, T; Pilch, P F

Partially purified human placental insulin receptor preparations give rise to three distinct insulin-binding peaks when eluted from a Mono Q high-performance liquid chromatography anion-exchange column. The authors analyzed the basis for this phenomenon by affinity cross-linking of insulin to each peak, followed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. They find that the three insulin-binding peaks represent different molecular weight complexes with the following subunit composition: (..cap alpha beta..)/sub 2/, (..cap alpha beta..)(..cap alpha beta..'), and (..cap alpha beta..')/sub 2/, where ..beta..' represents a proteolytically derived fragment of the ..beta.. subunit. This analysis of subunit composition was confirmed by silver staining of affinity-purified insulin receptor following resolution of the forms on a Mono Q column as described previously. They have characterized the three isolated insulin receptor forms with regard to ligand binding by LIGAND and Scatchard analysis. They also measured insulin-stimulatable autophosphorylation and exogenous kinase activity directed toward poly(Glu/Tyr) (4:1). The three forms of the insulin receptor exhibit similar K/sub D/'s for insulin binding to the high- and low-affinity sites. These results demonstrate that only the intact (..cap alpha beta..)/sub 2/ form of the insulin receptor has the ability to undergo insulin-stimulated kinase activity. The conversion of only one ..beta.. subunit to the ..beta..' subunit is enough to render the receptor incapable of ligand-induced autophosphorylation. However, the data also indicate that loss of one (or both) kinase domain(s) has no dramatic effect on the ability of the receptor's binding sites to interact with insulin.

• Research Organization: Boston Univ. School of Medicine, MA (USA)
• OSTI ID: 7002616
• Journal Information: Biochemistry; (United States), Journal Name: Biochemistry; (United States) Vol. 27:15; ISSN BICHA
• Country of Publication: United States
• Language: English

Related Subjects

550201* -- Biochemistry-- Tracer Techniques
59 BASIC BIOLOGICAL SCIENCES
AUTORADIOGRAPHY
BETA DECAY RADIOISOTOPES
CHEMICAL REACTIONS
CHROMATOGRAPHY
DAYS LIVING RADIOISOTOPES
DECOMPOSITION
ELECTRON CAPTURE RADIOISOTOPES
ELECTROPHORESIS
ENZYMES
FETAL MEMBRANES
HORMONES
INSULIN
INTERMEDIATE MASS NUCLEI
IODINE 125
IODINE ISOTOPES
ION EXCHANGE CHROMATOGRAPHY
ISOTOPES
LIGANDS
MEMBRANE PROTEINS
MEMBRANES
MOLECULAR STRUCTURE
MOLECULAR WEIGHT
NUCLEI
ODD-EVEN NUCLEI
ORGANIC COMPOUNDS
PEPTIDE HORMONES
PHOSPHORUS-GROUP TRANSFERASES
PHOSPHOTRANSFERASES
PLACENTA
PROTEINS
PROTEOLYSIS
RADIOISOTOPES
RECEPTORS
SEPARATION PROCESSES
TRANSFERASES