The Binding of Insulin and Somatomedin a to Human Placental Membrane

Takano, Kazue; Hall, K.; Fryklund, Linda; Holmgren, Arne; Sievertsson, Hans; Uthne, Knut

doi:10.1530/acta.0.0800014

Cited by 76 publications

(44 citation statements)

References 17 publications

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“…The placenta contains receptors for several peptide hormones including insulin [23], epidermal growth factor [24], the somatomedins [25][26][27] and gonadotrophin releasing hormone [28] and has been used as a source of receptor for the purification of several of these. In this study we have identified, and characterized, CT receptors in a human placental membrane fraction.…”

Section: Introductionmentioning

confidence: 99%

Human placental calcitonin receptors

Nicholson

D’Santos

Evans

et al. 1988

Biochemical Journal

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Receptors for the hypocalcaemic hormone, calcitonin (CT), have been identified in a membrane fraction prepared from term human placentae. Binding of 125I-labelled salmon CT (125I-sCT) to the membranes was time- and temperature-dependent, saturable (Bmax. 58 +/- 11 fmol/mg of protein), of high affinity (Kd 80 +/- 21 pM) and poorly reversible. Species-specific CTs and CT analogues competed for 125I-sCT binding with potencies proportional to their known biological potencies. Various unrelated peptide hormones did not compete, indicating that receptor binding was specific for CT. Photoaffinity labelling using a derivatized biologically active sCT analogue, [Arg11,18,3-nitrophenylazide-Lys14]sCT, identified a receptor component of Mr approximately 85,000, comparable with findings in osteoclasts and other target cells. The presence of CT receptors in the human placenta supports other evidence that CT may have a role in the regulation of placental function.

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Section: Introductionmentioning

confidence: 99%

Human placental calcitonin receptors

Nicholson

D’Santos

Evans

et al. 1988

Biochemical Journal

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“…The MSA receptor in hiunim placenta can be compared with the receptors for insulin (Posner, 1974), somatomedin A (Takano et al, 1975) and somatomedin C (D'Ercole et al, 1976) in this tissue. All have similar properties of time, temperature and pH dependence as well as reversibility of binding by lowering the pH.…”

Section: Discussionmentioning

confidence: 99%

The Binding of Rat Liver Cell Multiplication‐stimulating Activity (Msa) to Human Placenta and Serum Proteins

Brinsmead

Liggins

1978

Aust J Exp Biol Med

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Summary Multiplication‐stimulating activity (MSA) from the medium of BRL‐3A rat liver cells in culture binds to cell membrane and cytosol receptors from human placenta and to serum proteins. The binding of MSA to placental cell membranes is dependent on time, temperature, pH and divalent ion concentration. MSA bound to placental cytosol receptor and serum is not displaced by insulin, whereas that bound to placental cell membranes is displaced by insulin and insulin‐like peptides. The affinity of the three receptors for MSA is similar (≏ 108 M ‐1). An assay using 125I‐MSA and placental membrane receptor detects somatomedin‐like receptor activity (SmLRA) in unextracted sera from man and animals. A binding protein in serum that competes for 125I‐MSA with receptor could not be completely separated from SmLRA by‐heating, acidification, charcoal treatment and gel chromatography of the serum. The relative activities of SmLRA and serum binding protein remained constant in three disorders of human growth (acromegaly, growth hormone deficiency and Laron's dwarfism) in which values of SmLRA varied widely. However, the binding protein is only partly responsible for the apparent SmLRA of unextracted serum. It is concluded that MSA is a suitable radioligand for the investigation of somatomedin disorders in man either by receptor assays or by studies of tissue receptors.

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“…Interest in these particular hormones/factors as modulators of placental metabolism has been fuelled, in part, by the demonstration of specific, membrane-associated receptors in the human placenta (25,36,38,43,46,48,54,57), two of which (for insulin and EGF-URO) have been partially purified (26,28,60). Placental cytosolic binding proteins for some of the IGFs have also been described (7,22).…”

Section: Speculationmentioning

confidence: 99%