Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P50583 (asymmetrical)
 12,197 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We describe the distribution of type II insulin-like growth factor receptors among canalicular (cLPM) and basolateral (bLPM) subfractions of rat liver plasma membranes (LPM). BLPM bound 3 times more 125I-IGF II than cLPM. The number of receptors was (1.3 +/- 0.15) X 10(-12) mol/mg in bLPM, and (0.4 +/- 0.17) X 10(-12) mol/mg in cLPM. Insulin-like growth factor II (IGF II) was 10 times more potent than insulin-like growth factor I (IGF I) in displacing 125I-IGF II from both basolateral and canalicular binding sites. Insulin did not interfere with binding of 125I-IGF II in either LPM preparations. Our findings point to an asymmetrical hepatocellular distribution of type II IGF receptors, thus extending the concept of surface polarization of hepatocytes to growth promoting hormone receptors.
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PMID:Polar surface distribution of type II insulin-like growth factor receptor in rat hepatocytes. 217 7

To characterize the distribution of receptors for insulin-like growth factors I and II (IGF I and II) in the plasma membrane of the renal proximal tubular cell, we measured binding of 125I-labeled IGF I and 125I-labeled IGF II to proximal tubular basolateral and brush-border membranes and characterized IGF I-stimulated phosphorylation of detergent-solubilized membranes. 125I-IGF I bound primarily to a 135,000 relative molecular weight (Mr) protein and IGF II to a 260,000 Mr protein in isolated membranes. Binding of 125I-IGF I was severalfold greater in basolateral than in brush-border membranes. IGF I-stimulated phosphorylation of the 92,000 Mr beta-subunit of its receptor could be demonstrated only in basolateral membranes. These findings are consistent with an asymmetrical distribution of receptors for IGF I in the plasma membrane of the renal proximal tubular cell, localization being primarily on the basolateral side. In contrast, binding of 125I-IGF II to isolated basolateral and brush-border membranes was equivalent, suggesting that receptors for this peptide are distributed more symmetrically in the plasma membrane. Our findings suggest that the actions of IGF I in proximal tubule are mediated via interaction of circulating peptide with specific receptors in the basolateral membrane. However, our findings establish the potential for actions of IGF II to be exerted in proximal tubule via interaction with both basolateral and/or brush-border membrane receptors.
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PMID:Distribution of IGF receptors in the plasma membrane of proximal tubular cells. 296 Dec 73