Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
32
pubmed:dateCreated
2001-8-6
pubmed:abstractText
The glycoprotein hormone family represents a class of heterodimers, which include the placental hormone human chorionic gonadotropin (CG) and the anterior pituitary hormones follitropin, lutropin, and thyrotropin. They are composed of common alpha subunit and a hormone-specific beta subunit. Based on the CG crystal structure, it was suggested that the quaternary subunit interactions are crucial for biological activity. However, recent observations using single chain glycoprotein hormone analogs, where the beta and alpha subunits are linked (NH(2)-CGbeta-alpha; CGbetaalpha orientation), implied that the heterodimeric-like quaternary configuration is not a prerequisite for receptor binding/signal transduction. To study the heterodimeric alignment of the two subunit domains in a single chain and its role in the intracellular behavior and biological action of the hormone, a single chain CG variant was constructed in which the carboxyl terminus of alpha was fused to the CGbeta amino terminus (NH(2)-alpha-CGbeta; alphaCGbeta orientation). The secretion rate of alphaCGbeta from transfected Chinese hamster ovary cells was less than that seen for CGbetaalpha. The alphaCGbeta tether was not recognized by dimer-specific monoclonal antibodies and did not bind to lutropin/CG receptor. To define if one or both subunit domains were modified in alphaCGbeta, it was co-transfected with a monomeric alpha or CGbeta gene. In each case, alphaCGbeta/alpha and alphaCGbeta/CGbeta complexes were formed indicating that CG dimer-specific epitopes were established. The alphaCGbeta/alpha complex bound to receptor indicating that the beta domain in the alphaCGbeta tether was still functional. In contrast, no significant receptor binding of alphaCGbeta/CGbeta was observed indicating a major perturbation in the alpha domain. These results suggest that although dimeric-like determinants are present in both alphaCGbeta/alpha and alphaCGbeta/CGbeta complexes, the receptor binding determinants in the alpha domain of the tether are absent. These results show that generating heterodimeric determinants do not necessarily result in a bioactive molecule. Our data also indicate that the determinants for biological activity are distinct from those associated with intracellular behavior.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Aug
pubmed:issn
0021-9258
pubmed:author
pubmed:issnType
Print
pubmed:day
10
pubmed:volume
276
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
29871-9
pubmed:dateRevised
2006-11-15
pubmed:meshHeading
pubmed-meshheading:11390409-Animals, pubmed-meshheading:11390409-Blotting, Western, pubmed-meshheading:11390409-CHO Cells, pubmed-meshheading:11390409-Chorionic Gonadotropin, pubmed-meshheading:11390409-Cricetinae, pubmed-meshheading:11390409-Cyclic AMP, pubmed-meshheading:11390409-Dimerization, pubmed-meshheading:11390409-Dose-Response Relationship, Drug, pubmed-meshheading:11390409-Epitopes, pubmed-meshheading:11390409-Humans, pubmed-meshheading:11390409-Kinetics, pubmed-meshheading:11390409-Ligands, pubmed-meshheading:11390409-Protein Binding, pubmed-meshheading:11390409-Protein Conformation, pubmed-meshheading:11390409-Protein Structure, Quaternary, pubmed-meshheading:11390409-Protein Structure, Tertiary, pubmed-meshheading:11390409-Signal Transduction, pubmed-meshheading:11390409-Time Factors, pubmed-meshheading:11390409-Transfection
pubmed:year
2001
pubmed:articleTitle
The position of the alpha and beta subunits in a single chain variant of human chorionic gonadotropin affects the heterodimeric interaction of the subunits and receptor-binding epitopes.
pubmed:affiliation
Department of Molecular Biology and Pharmacology, Washington University School of Medicine, St. Louis, Missouri 63110, USA.
pubmed:publicationType
Journal Article, Research Support, U.S. Gov't, P.H.S., Research Support, Non-U.S. Gov't