Portal de Periódicos da CAPES

Five Out of Six Tryptophan Residues in the N -Terminal Extracellular Domain of the Rat GLP-1 Receptor Are Essential for its Ability to Bind GLP-1

1997; Elsevier BV; Volume: 18; Issue: 2 Linguagem: Inglês

10.1016/s0196-9781(96)00321-x

1873-5169

Andreas Wilmen, Brigitte Van Eyll, Burkhard Göke, Rüdiger Göke,

Neuropeptides and Animal Physiology

Wilmen, A., B. Van Eyll, B. GÖKe and R. GÖKe. Five out of six tryptophan residues in the N-terminal extracellular domain of the rat Glp-1 receptor are essential for its ability to bind Glp-1. Peptides 18(2) 301–305, 1997.—Oligonucleotide-directed mutagenesis was utilized to investigate the requirement of tryptophan residues located in the N-terminal domain of the glucagon-like peptide-1 (GLP-1) receptor for the ability to bind its ligand and to induce cAMP generation. W39, W72, W87, W91, W110, and W120 were mutated into alanine. Two of the six tryptophan residues, W72 and W110, are highly conserved within the receptor subfamily. After transfection of mutated cDNAs in COS-7 or CHL cells, it appeared that mutant W87A bound [125I]GLP-1 with the same affinity as wild-type receptor and induced signal transduction to a comparable extent. In contrast, mutant receptors W39A, W72A, W91A, W110A, and W120A lost the ability to bind [125I]GLP-1. Because all mutated receptor cDNAs were transcribed on RNA level (Northern blot) and the receptor proteins were expressed at the plasma membrane level (Western blot), it is concluded that with the exception of W87 all tryptophan residues are essential for receptor ligand interaction. This indicates the significance of hydrophobic interactions within the N-terminal domain of the GLP-1 receptor.