Linked Life Data

6761200

Source:http://linkedlifedata.com/resource/pubmed/id/6761200

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
7
pubmed:dateCreated
1983-4-7
pubmed:abstractText
Filtered proteins including insulin are absorbed in the proximal tubule by means of pinocytosis. The first step in this process is binding of the protein to brush border membrane. As it is not known whether absorption exhibits specificity, we set out to determine whether specific binding sites for insulin are present in brush border membranes. Rabbit-isolated brush border membranes were incubated with 125I-insulin and varying concentrations of cold insulin or other peptide hormones. Binding and degradation of 125I-insulin occurred in a time- and temperature-dependent manner. Native insulin competitively inhibited 125I-insulin binding, but calcitonin, arginine vasopressin, glucagon, and growth hormone (10(-6) M) were relatively ineffective. Nonspecific binding averaged one-third of the total radioactivity bound. Scatchard analysis of binding data revealed two classes of insulin receptors: high affinity, low capacity receptors and low affinity, high capacity receptors. Gel filtration analysis of 125I-insulin exposed to brush border membrane revealed the formation of low-molecular-weight products similar to that produced by intact kidneys. The degrading process exhibited some specificity, for cold insulin (10(-6) M) was more effective than calcitonin, vasopressin, glucagon, or growth hormone in inhibiting degradation (32% versus less than 13% inhibition; P less than 0.01). Whether this reflects inhibition of insulin specific binding before exposure to degradation or inhibition of specific enzymes is unclear. In summary, it appears that renal brush border membranes have a major insulin-specific receptor component that could potentially mediate tubular insulin absorption. In addition, there is a smaller nonspecific component that may also have the potential to mediate insulin absorption. Finally, it appears that brush border membranes have the ability to degrade insulin to low-molecular-weight products by a process that exhibits some specificity for insulin.
pubmed:grant
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
AIM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Jul
pubmed:issn
0012-1797
pubmed:author
pubmed:issnType
Print
pubmed:volume
31
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
618-23
pubmed:dateRevised
2011-11-17
pubmed:meshHeading
pubmed:year
1982
pubmed:articleTitle
Binding and degradation of insulin by isolated renal brush border membranes.
pubmed:publicationType
Journal Article, Research Support, U.S. Gov't, P.H.S., Research Support, Non-U.S. Gov't