The world's first wiki where authorship really matters (Nature Genetics, 2008). Due credit and reputation for authors. Imagine a global collaborative knowledge base for original thoughts. Search thousands of articles and collaborate with scientists around the globe.

wikigene or wiki gene protein drug chemical gene disease author authorship tracking collaborative publishing evolutionary knowledge reputation system wiki2.0 global collaboration genes proteins drugs chemicals diseases compound
Hoffmann, R. A wiki for the life sciences where authorship matters. Nature Genetics (2008)
 
 
 
 
 

Mannose-6-phosphate enhances cross-linking efficiency between insulin-like growth factor-II (IGF-II) and IGF-II/mannose-6-phosphate receptors in membranes.

Endogenous and exogenous phosphomannosyl ligands inhibit binding of insulin-like growth factor-II (IGF-II) to the IGF-II/mannose-6-phosphate receptor (IGF-II/Man-6-P receptor). In the present study, the mechanism of this antagonism was examined using a [125I]IGF-II cross-linking assay with disuccinimidyl suberate in cell membranes. Treatment with 5 mM Man-6-P enhanced [125I]IGF-II cross-linking to the receptor. The magnitude of the Man-6-P enhancement differed depending on the source of the membranes, ranging from a 30% increase in JEG-3 human choriocarcinoma up to a 560% increase in B16-F1 mouse melanoma. Man-6-P stimulated [125I]IGF-II-receptor cross-linking in H-35 hepatoma membranes by about 80%, even at concentrations of labeled IGF-II (greater than or equal to 10 nM) that nearly saturated the receptors. Thus, in addition to its effect on IGF-II-binding affinity, Man-6-P caused a 1.5- to 2-fold increase in cross-linking efficiency within the IGF-II-receptor complex. Furthermore, Man-6-P enhanced [125I]IGF-II cross-linking to the H-35 receptor by a constant (approximately 80%) increment 1) when the cross-linking reaction was conducted in buffers of different pH over the range 6.8-8.0, or 2) using cross-linking agents differing in spacer arm length from 6.4-16.1 A. Washing membranes before assay with either Man-6-P (pH 7.4) or 0.5 M NaCl (pH 4.5) reduced the subsequent Man-6-P enhancement of [125I]IGF-II-receptor cross-linking, suggesting that this phenomenon was actually due to displacement of inhibitory phosphomannosyl ligands bound endogenously to the Man-6-P sites of the receptor. In support of this hypothesis, Man-6-P produced a minimal (8-14%) enhancement of [125I]IGF-II-receptor cross-linking in membranes from I-cell fibroblasts lacking such phosphomannosyl ligands. Thus, phosphomannosyl ligands bound to the IGF-II/Man-6-P receptor decrease both IGF-II- binding affinity and IGF-II-receptor cross-linking efficiency. Membrane-associated receptors appear to exist in experimentally and perhaps functionally distinct populations, depending on occupancy of the Man-6-P-binding sites.[1]

References

 
WikiGenes - Universities