Relationship between the subunit structure of insulin receptor and its competence to bind insulin and undergo phosphorylation

Insulin receptor partially purified from human placenta by chromatography on immobilized wheat germ agglutinin was subjected to affinity cross linking to determine the relationship between the subunit structure of the multiple forms of the insulin receptor and their competence to bind insulin and undergo autophosphorylation. It was demonstrated that, whereas the 340-kDa intact receptor undergoes autophosphorylation, the 290- and 320-kDa insulin binding forms of the receptor do not. Phosphorylation at tyrosyl residues in the intact receptor was verified using a new facile method for determination of phosphorylated amino acids. The competence of the phosphorylated 340-kDa protein to bind insulin was demonstrated using a double-probe labeling protocol wherein receptor phosphorylated with [γ-³²P]ATP was cross-linked with disuccinimidyl suberate (DSS) in the presence of N^?B29-biotinylinsulin. The observation that succinylavidin, by virtue of its interaction with biotinyl residues, decreased the electrophoretic mobility of receptor radiochemically labeled with ³²P indicated that the phosphorylated 340-kDa protein was competent to bind insulin. This result is compelling evidence that the 340-kDa phosphorylated species is insulin receptor itself, rather than a closely associated contaminant. Treatment of the receptor with the crosslinking agent DSS produced (after reduction and denaturation) α-dimer, β-dimer, and a smaller amount of tetramer. This observation is consistent with a symmetrical, tetrameric, α₂β₂structure for insulin receptor from human placenta, and excludes previously proposed alternative structures containing one α and One β Chain.     

Chemiluminescence,suppression and cytotoxicity in peripheral blood mononuclear cells from solid tumor cancer patients

Summary Chemiluminescence, indomethacin-sensitive suppression, and adherent cell cytotoxicity were measured in peripheral blood mononuclear cells (PBMC) from normal subjects and solid tumor cancer patients. These functions were found to be differentially affected by malignant disease. In cancer patients with disseminated disease, indomethacin-sensitive suppression and chemiluminescence emission were increased to a level significantly higher than normal without a concurrent increase in adherent cell cytotoxic function. In cancer patients with at most minimum residual diseases, the levels of chemiluminescence, indomethacin-sensitive suppression, and adherent cell cytotoxicity found were comparable to those of the normal study population. In vitro stimulation of cells from patients with disseminated disease by phorbol myristic acetate (PMA) increased chemiluminescence overcame the suppressive effects of indomethacin-sensitive suppressor cells, and increased adherent cell cytotoxicity; in cells from patients with at most minimum residual disease, PMA increased chemiluminescence and cytotoxicity without influencing the activity of indomethacin-sensitive suppressor cells. Vaccination of lung cancer patients with Freund's complete adjuvant or Freund's complete adjuvant plus tumor antigen extracts led to increased levels of chemiluminescence and increased levels of adherent cell cytotoxicity without altering indomethacin-sensitive regulatory cell function.     

Formation of polarized contractile interfaces by self-organized Toll-8/Cirl GPCR asymmetry

1. Download : Download high-res image (159KB)
2. Download : Download full-size image

     

Cross-reactivity of SARS-CoV structural protein antibodies against SARS-CoV-2

1. Download : Download high-res image (298KB)
2. Download : Download full-size image

     

Serial immune function testing to predict clinical disease relapse in patients with solid tumors

Cancer Immunology, Immunotherapy -