Dietrich Brandenburg

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A method was developed to determine the interspin distances of two or more nitroxide spin labels attached to specific sites in proteins. This method was applied to different conformations of spin-labeled insulins. The electron paramagnetic resonance (EPR) line broadening due to dipolar interaction is determined by fitting simulated EPR powder spectra to(More)
The E1 glycoprotein of coronavirus mouse hepatitis virus A59 was synthesized in vitro by translation of viral mRNA in the presence of dog pancreatic microsomes. Its disposition in the membrane was investigated by digestion with proteases and by selective NH2-terminal labeling. The protein spans the membrane, but only small portions from the NH2 and COOH(More)
We have followed the fate of cell surface insulin receptors in isolated rat hepatocytes by both a biochemical and a morphological approach. Hepatocytes were labeled with the photoreactive and biologically active 125I-labeled insulin analogue, [2-nitro-4-azidophenylacetylB2]des-PheB1-insulin, under conditions that allow for minimal internalization (2 hr at(More)
There is morphological and biochemical evidence that insulin is internalized in hepatocytes. The present study was designed to investigate the fate of the insulin receptor itself, subsequently to the initial binding step of the hormone to the hepatocyte plasma membrane. The insulin receptor was labeled with a 125I-photoreactive insulin analogue(More)
Using the photoreactive, biologically active insulin analogue, B2-(2 nitro, 4-azidophenylacetyl)des-PheB1 insulin, which can be covalently bound to receptor molecules upon photolysis, the insulin receptor has been studied in three different types of cells or tissues: isolated rat hepatocytes, intact murine soleus muscle and cultured human lymphocytes. When(More)
Chimeric insulin/insulin-like growth factor-1 receptors and insulin receptor alpha-subunit point mutants were characterized with respect to their binding properties for insulin and insulin-like growth factor-1 (IGF-1) and their ability to translate ligand interaction into tyrosine kinase activation in intact cells. We found that replacement of the(More)
The translocation of occupied surface insulin receptors to the nuclei of isolated hepatocytes was studied using the biologically active photosensitive insulin derivative, B2(2-nitro-4-azidophenylacetyl)-des-PheB1-insulin (NAPA-DP-insulin). When hepatocytes were photolabeled at 4 degrees C, extensively washed, and then further incubated at 37 degrees C for 1(More)
In order to study the role of the amino acid in position B25 and its environment in shortened insulins, a series of analogues was prepared with the following modifications: 1, Stepwise shortening of the B-chain including replacements of TyrB26 and ThrB27 by glycine; 2, substitutions at the carboxamide nitrogen of des-(B26-B30)-insulin-B25-amide by apolar,(More)
In the present study we describe the antagonistic effects of the covalently dimerized insulin derivative B29,B29'-suberoyl-insulin on insulin receptors in 3T3-L1 mouse cells. In differentiated 3T3-L1 adipocytes, the derivative fully inhibits binding of 125I-labeled insulin to its receptor with about the same affinity as unlabeled insulin. In contrast, the(More)