Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
5
pubmed:dateCreated
1992-3-17
pubmed:abstractText
Agonist-regulated redistribution of human beta 2-adrenergic receptors was examined in 293 cells. A specific antiserum recognizing the carboxyl-terminal hydrophilic domain of the receptor was developed, characterized, and used for immunocytochemical localization of receptors in fixed cells by conventional fluorescence and confocal fluorescence microscopy. The beta-adrenergic agonist isoproterenol induced redistribution of receptors from the surface of cells into small (less than 1 micron diameter) punctuate accumulations which were detected in cells within 2 min of agonist addition. The time course of receptor redistribution paralleled that of receptor sequestration measured by ligand binding, and receptor redistribution was reversible in the presence of the beta-adrenergic antagonist alprenolol. Optical sections imaged through cells by confocal microscopy localized receptor accumulations within the cytoplasm. To address the question of receptor internalization further, a mutant receptor possessing an engineered antigenic epitope in the amino-terminal hydrophilic domain was constructed, transfected into cells, and localized using both a monoclonal antibody recognizing the epitope tag (receptor ectodomain) and an antiserum recognizing the carboxyl terminus (receptor endodomain). In untreated cells most receptor antigen was detected at the cell surface, as assessed by accessibility to ectodomain antibodies in unpermeabilized specimens. In isoproterenol-treated cells, however, little receptor antigen was detected at the cell surface. Punctate receptor accumulations present in isoproterenol-treated cells were labeled by antibodies only following permeabilization of cells, as expected if these receptor accumulations were intracellular. Finally, internalized beta-adrenergic receptors colocalized with transferrin receptors, which are markers of endosomal membranes. These data provide several lines of evidence establishing that beta-adrenergic receptors undergo ligand-regulated internalization, they suggest that internalized receptors may be recycled back to the cell surface, and they provide the first direct indication that these processes involve the same endosomal membrane system passaged by constitutively recycling receptors.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Feb
pubmed:issn
0021-9258
pubmed:author
pubmed:issnType
Print
pubmed:day
15
pubmed:volume
267
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
3530-8
pubmed:dateRevised
2006-11-15
pubmed:meshHeading
pubmed-meshheading:1371121-Alprenolol, pubmed-meshheading:1371121-Amino Acid Sequence, pubmed-meshheading:1371121-Antibodies, Monoclonal, pubmed-meshheading:1371121-Cell Line, pubmed-meshheading:1371121-Cell Membrane, pubmed-meshheading:1371121-Epitopes, pubmed-meshheading:1371121-Fluorescent Antibody Technique, pubmed-meshheading:1371121-Humans, pubmed-meshheading:1371121-Immunoblotting, pubmed-meshheading:1371121-Isoproterenol, pubmed-meshheading:1371121-Kinetics, pubmed-meshheading:1371121-Ligands, pubmed-meshheading:1371121-Models, Biological, pubmed-meshheading:1371121-Molecular Sequence Data, pubmed-meshheading:1371121-Mutagenesis, Site-Directed, pubmed-meshheading:1371121-Organelles, pubmed-meshheading:1371121-Receptors, Adrenergic, beta, pubmed-meshheading:1371121-Receptors, Transferrin, pubmed-meshheading:1371121-Transfection
pubmed:year
1992
pubmed:articleTitle
Ligand-regulated internalization and recycling of human beta 2-adrenergic receptors between the plasma membrane and endosomes containing transferrin receptors.
pubmed:affiliation
Department of Cardiovascular Medicine, Howard Hughes Medical Institute, Stanford Medical Center, California 94305.
pubmed:publicationType
Journal Article, Research Support, Non-U.S. Gov't