A specific insulin receptor and tyrosine kinase activity in the membranes of Neurospora crassa.
Cells of the wall-less ("slime") strain of Neurospora crassa possess specific high affinity insulin binding sites on their cell surface. 125I-labeled bound insulin was not displaced from these cells by insulin-like growth factor II (IGF-II), and was only weakly displaced by IGF-I and proinsulin. Cross-linking of 125I-labeled insulin with N. crassa cells using disuccinimidyl suberate resulted in the labeling of a single band of ca. 67 kDa m.w. on a polyacrylamide gel. Two proteins of ca. 66 and 59 kDa m.w. were purified from detergent solubilized plasma membrane preparations by passage over an insulin-agarose affinity matrix. Antibodies against an autophosphorylation site on the human and Drosophila insulin receptors (anti P2) immunoprecipitated a single phosphoprotein of ca. 50 kDa m.w. from detergent solubilized plasma membranes, which possessed protein tyrosine kinase activity when histone H2 was used as substrate.
Fawell
S E
SE
Department of Physiology and Biophysics, University of Medicine and Dentistry of New Jersey, Piscataway 08854.
Lenard
J
J
D002462:Cell Membrane / Q000201:enzymology / Q000378:metabolism; D002846:Chromatography, Affinity; D003429:Cross Reactions; D009491:Neurospora / Q000378:metabolism*; D009492:Neurospora crassa / Q000201:enzymology / Q000378:metabolism*; D010766:Phosphorylation; D011233:Precipitin Tests; D011505:Protein-Tyrosine Kinases / Q000302:isolation & purification / Q000378:metabolism*; D011972:Receptor, Insulin / Q000276:immunology / Q000378:metabolism*
D011505:Protein-Tyrosine Kinases; D011972:Receptor, Insulin