Segmental distribution of epidermal growth factor binding sites in rabbit nephron. 1990

M D Breyer, and R Redha, and J A Breyer
Department of Medicine, Vanderbilt University, Nashville, Tennessee 37212.

The kidney possesses epidermal growth factor (EGF) receptors and is a major site of synthesis for the EGF precursor, prepro-EGF. To examine the segmental localization of EGF receptors in the rabbit kidney, we characterized 125I-labeled EGF binding to micro-dissected rabbit nephron segments. Specific binding constituted 70-80% of total binding and was saturable with an apparent Kd of 8 nM. Kinetic studies (0 degrees C) revealed an association t1/2 of 20.7 min and a dissociation t1/2 of 27 min. Competition studies revealed that 125I-EGF binding was inhibited by unlabeled EGF or its homologue transforming growth factor-alpha, but not by parathyroid hormone or insulin. Mapping studies showed specific 125I-EGF binding (attomoles per centimeter) was highest in proximal straight tubules, followed by proximal convoluted tubules, cortical collecting ducts, inner medullary collecting ducts, outer medullary collecting ducts, and distal convoluted tubules. Specific binding to glomeruli was also observed. Interestingly, no specific binding of 125I-EGF to thick ascending limbs, a site of EGF precursor synthesis, was observed. These studies suggest potential sites of action for EGF in the rabbit kidney.

UI MeSH Term Description Entries
D007700 Kinetics The rate dynamics in chemical or physical systems.
D009399 Nephrons The functional units of the kidney, consisting of the glomerulus and the attached tubule. Nephron
D011817 Rabbits A burrowing plant-eating mammal with hind limbs that are longer than its fore limbs. It belongs to the family Leporidae of the order Lagomorpha, and in contrast to hares, possesses 22 instead of 24 pairs of chromosomes. Belgian Hare,New Zealand Rabbit,New Zealand Rabbits,New Zealand White Rabbit,Rabbit,Rabbit, Domestic,Chinchilla Rabbits,NZW Rabbits,New Zealand White Rabbits,Oryctolagus cuniculus,Chinchilla Rabbit,Domestic Rabbit,Domestic Rabbits,Hare, Belgian,NZW Rabbit,Rabbit, Chinchilla,Rabbit, NZW,Rabbit, New Zealand,Rabbits, Chinchilla,Rabbits, Domestic,Rabbits, NZW,Rabbits, New Zealand,Zealand Rabbit, New,Zealand Rabbits, New,cuniculus, Oryctolagus
D004815 Epidermal Growth Factor A 6-kDa polypeptide growth factor initially discovered in mouse submaxillary glands. Human epidermal growth factor was originally isolated from urine based on its ability to inhibit gastric secretion and called urogastrone. Epidermal growth factor exerts a wide variety of biological effects including the promotion of proliferation and differentiation of mesenchymal and EPITHELIAL CELLS. It is synthesized as a transmembrane protein which can be cleaved to release a soluble active form. EGF,Epidermal Growth Factor-Urogastrone,Urogastrone,Human Urinary Gastric Inhibitor,beta-Urogastrone,Growth Factor, Epidermal,Growth Factor-Urogastrone, Epidermal,beta Urogastrone
D000818 Animals Unicellular or multicellular, heterotrophic organisms, that have sensation and the power of voluntary movement. Under the older five kingdom paradigm, Animalia was one of the kingdoms. Under the modern three domain model, Animalia represents one of the many groups in the domain EUKARYOTA. Animal,Metazoa,Animalia
D001665 Binding Sites The parts of a macromolecule that directly participate in its specific combination with another molecule. Combining Site,Binding Site,Combining Sites,Site, Binding,Site, Combining,Sites, Binding,Sites, Combining
D001667 Binding, Competitive The interaction of two or more substrates or ligands with the same binding site. The displacement of one by the other is used in quantitative and selective affinity measurements. Competitive Binding
D014018 Tissue Distribution Accumulation of a drug or chemical substance in various organs (including those not relevant to its pharmacologic or therapeutic action). This distribution depends on the blood flow or perfusion rate of the organ, the ability of the drug to penetrate organ membranes, tissue specificity, protein binding. The distribution is usually expressed as tissue to plasma ratios. Distribution, Tissue,Distributions, Tissue,Tissue Distributions
D066246 ErbB Receptors A family of structurally related cell-surface receptors that signal through an intrinsic PROTEIN-TYROSINE KINASE. The receptors are activated upon binding of specific ligands which include EPIDERMAL GROWTH FACTORS, and NEUREGULINS. EGF Receptor,Epidermal Growth Factor Receptor,Epidermal Growth Factor Receptor Family Protein,Epidermal Growth Factor Receptor Protein-Tyrosine Kinase,ErbB Receptor,HER Family Receptor,Receptor, EGF,Receptor, Epidermal Growth Factor,Receptor, TGF-alpha,Receptor, Transforming-Growth Factor alpha,Receptor, Urogastrone,Receptors, Epidermal Growth Factor-Urogastrone,TGF-alpha Receptor,Transforming Growth Factor alpha Receptor,Urogastrone Receptor,c-erbB-1 Protein,erbB-1 Proto-Oncogene Protein,EGF Receptors,Epidermal Growth Factor Receptor Family Proteins,Epidermal Growth Factor Receptor Kinase,HER Family Receptors,Proto-oncogene c-ErbB-1 Protein,Receptor Tyrosine-protein Kinase erbB-1,Receptor, ErbB-1,Receptors, Epidermal Growth Factor,Epidermal Growth Factor Receptor Protein Tyrosine Kinase,ErbB-1 Receptor,Family Receptor, HER,Family Receptors, HER,Proto oncogene c ErbB 1 Protein,Proto-Oncogene Protein, erbB-1,Receptor Tyrosine protein Kinase erbB 1,Receptor, ErbB,Receptor, ErbB 1,Receptor, HER Family,Receptor, TGF alpha,Receptor, Transforming Growth Factor alpha,Receptors, EGF,Receptors, Epidermal Growth Factor Urogastrone,Receptors, ErbB,Receptors, HER Family,c erbB 1 Protein,c-ErbB-1 Protein, Proto-oncogene,erbB 1 Proto Oncogene Protein
D066298 In Vitro Techniques Methods to study reactions or processes taking place in an artificial environment outside the living organism. In Vitro Test,In Vitro Testing,In Vitro Tests,In Vitro as Topic,In Vitro,In Vitro Technique,In Vitro Testings,Technique, In Vitro,Techniques, In Vitro,Test, In Vitro,Testing, In Vitro,Testings, In Vitro,Tests, In Vitro,Vitro Testing, In

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