Linked Life Data

1931947

Source:http://linkedlifedata.com/resource/pubmed/id/1931947

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
42
pubmed:dateCreated
1991-11-25
pubmed:abstractText
Members of the glycoprotein hormone family contain a common alpha subunit and a hormone-specific beta subunit. Human choriogonadotropin (hCG) beta is a 145 amino acid residue protein glycosylated at 6 positions (2 N-linked and 4 O-linked oligosaccharides). In an effort to elucidate receptor determinants on hCG beta, we have used site-directed mutagenesis to prepare and express several mutant cDNAs with replacements at arginines-43 and -94. Arg-43 is invariant in all known mammalian CG/lutropin beta amino acid sequences, and Arg-94 is conserved in 10 of the 12 sequences. Moreover, various studies involving synthetic peptides and enzymatic digestions of intact beta chains suggest that these residues may be important in hCG receptor binding. Point mutants were made in which these two arginines were replaced with the corresponding residues in human follitropin beta, Leu-43 and Asp-94. The wild-type and mutant beta chains were expressed in CHO cells containing a stably integrated gene for bovine alpha, and heterodimer formation occurred. These heterologous gonadotropins were active in assays using transformed Leydig cells, competitive binding with standard 125I-hCG, and cAMP and progesterone production, but the potency was considerably less than that associated with the hCG beta wild-type-containing gonadotropin. The double-mutant protein Arg-43 to Leu/Arg-94 to Asp also associated with bovine alpha, but the resultant heterodimer exhibited only low activity. Replacement of each arginine with lysine yielded heterodimers that were at least as potent as bovine alpha-hCG beta wild type, but the Lys-43-containing beta chain appeared to exhibit a low degree of subunit association or reduced stability relative to the expressed hCG beta wild type. These results demonstrate that arginines-43 and -94 contribute to receptor binding through a positive charge.
pubmed:grant
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Oct
pubmed:issn
0006-2960
pubmed:author
pubmed:issnType
Print
pubmed:day
22
pubmed:volume
30
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
10171-5
pubmed:dateRevised
2007-11-14
pubmed:meshHeading
pubmed:year
1991
pubmed:articleTitle
Contributions of arginines-43 and -94 of human choriogonadotropin beta to receptor binding and activation as determined by oligonucleotide-based mutagenesis.
pubmed:affiliation
Department of Biochemistry and Molecular Biology, University of Miami School of Medicine, Florida 33101.
pubmed:publicationType
Journal Article, Research Support, U.S. Gov't, P.H.S.